Demographic-economic paradox

Graph of Total Fertility Rate vs. GDP per capita of the corresponding country, 2004. Only countries with over 5 Million population were plotted to reduce outliers. Sources: CIA World Fact Book. For details, see List of countries and territories by fertility rate

Graph of Total Fertility Rate vs. GDP per capita of the corresponding country, 2004. Only countries with over 5 Million population were plotted to reduce outliers. Sources: CIA World Fact Book.

The demographic-economic paradox is the inverse correlation found between wealth and fertility within and between nations. The higher the degree of education and GDP per capita of a human population, subpopulation or social stratum, the fewer children are born in any industrialized country. In a 1974 UN population conference in Bucharest, Karan Singh, a former minister of population in India, illustrated this trend by stating "Development is the best contraceptive" [1]

The term 'paradox' comes from the notion that greater means would necessitate the production of more offspring as suggested by the influential Thomas Malthus.[2] Roughly speaking, nations or subpopulations with higher GDP per capita are observed to have fewer children, even though a richer population can support more children. Malthus held that in order to prevent widespread suffering, from famine for example, what he called 'moral restraint' (which included abstinence) was required. The demographic-economic paradox suggests that reproductive restraint arises naturally as a consequence of economic progress.

It is hypothesized that the observed trend has come about as a response to increased life expectancy, reduced childhood mortality, improved female literacy and independence, and urbanization that all result from increased GDP per capita,[3] consistent with the demographic transition model.

Demographic transition

Before the 19th century demographic transition of the western world, a minority of children would survive to the age of 20, and life expectancies were short even for those who reached adulthood. For example, in the 17th century in York, England 15% of children were still alive at age 15 and only 10% of children survived to age 20.[4]

Birth rates were correspondingly high, resulting in slow population growth. The agricultural revolution and improvements in hygiene then brought about dramatic reductions in mortality rates in wealthy industrialized countries, initially without affecting birth rates. In the 20th century, birth rates of industrialized countries began to fall, as societies became accustomed to the higher probability that their children would survive them. Cultural value changes were also contributors, as urbanization and female employment rose.

Since wealth is what drives this demographic transition, it follows that nations that lag behind in wealth also lag behind in this demographic transition. The developing world's equivalent Green Revolution did not begin until the mid-twentieth century. This creates the existing spread in fertility rates as a function of GDP per capita.

Religion

Another contributor to the demographic-economic paradox may be religion. Religious societies tend to have higher birth rates than secular ones, and richer, more educated nations tend to advance secularization. [4] This may help explain the Israeli and Saudi Arabian exceptions, the two notable outliers in the graph of fertility versus GDP per capita at the top of this article. In American media it is widely believed that America is also an exception to global trends. The current fertility rate in America is 2.09, higher than in most other developed countries.[5][6] This may be due to the United States having a high percentage of religious followers compared to Europe as a whole. [7]

The role of different religions in determining family size is complex. For example, the Catholic countries of southern Europe traditionally had a much higher fertility rate than was the case in Protestant northern Europe. However, economic growth in Spain, Italy, etc, has been accompanied by a particularly sharp fall in the fertility rate, to a level below that of the Protestant north. This suggests that the demographic-economic paradox applies more strongly in Catholic countries, although Catholic fertility started to fall when the liberalizing reforms of Vatican II were implemented. It remains to be seen if the fertility rate among (mostly Catholic) Hispanics in the U.S. will follow a similar pattern.

Another possible explanation for the "American exception" is its much higher rate of teenage pregnancies,[5] particularly in the southern US,[6] compared to other countries with effective sexual education; this does not contradict the religious-beliefs hypothesis.

In his book America Alone: The End of the World as We Know It, Mark Steyn asserts that the United States has higher fertility rates because of its greater economic freedom compared to other industrialized countries. However, the countries with the highest assessed economic freedom, Hong Kong and Singapore, have significantly lower birthrates than the United States. According to the Index of Economic Freedom, Hong Kong is the most economically free country in the world[7]. Hong Kong also has the world's lowest birth rate[8]. However, studies have also suggested a correlation between population density and fertility rate.[9][10][11] Hong Kong and Singapore have the third and fourth-highest population densities in the world. This may account for their very low birth rates despite high economic freedom. By contrast, the United States ranks 180 out of 241 countries and dependencies by population density.


Consequences

A reduction in fertility can lead to an ageing population which leads to a variety of problems, see for example the Demographics of Japan.

A related concern is that high birth rates tend to place a greater burden of child rearing and education on populations already struggling with poverty. Consequently, inequality lowers average education and hampers economic growth. [12] Also, in countries with a high burden of this kind, a reduction in fertility can drive economic growth as well as the other way around. [13]

Reproductive health

Within the framework of WHO's definition of health as a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity, reproductive health, or sexual health/hygiene, addresses the reproductive processes, functions and system at all stages of life.[1] Reproductive health, therefore, implies that people are able to have a responsible, satisfying and safe sex life and that they have the capability to reproduce and the freedom to decide if, when and how often to do so. Implicit in this are the right of men and women to be informed of and to have access to safe, effective, affordable and acceptable methods of fertility regulation of their choice, and the right of access to appropriate health care services that will enable women to go safely through pregnancy and childbirth and provide couples with the best chance of having a healthy infant.

According to the WHO, "Reproductive and sexual ill-health accounts for 20% of the global burden of ill-health for women, and 14% for men."[2]

Childbearing and health

Waiting until mother is at least 18 years old before trying to have children improves maternal and child health.[3]

If an additional child is desired, it is considered healthier for mother, as well as for the succeeding child, to wait at least 2 years after previous birth before attempting to conceive (but not more than 5 years).[3] After a miscarriage or abortion, it is healthier to wait at least 6 months.[3]

International Conference on Population and Development (ICPD), 1994

The International Conference on Population and Development (ICPD) was held in Cairo, Egypt, from 5 to 13 September 1994. Delegations from 179 States took part in negotiations to finalize a Programme of Action on population and development for the next 20 years. Some 20,000 delegates from various governments, UN agencies, NGOs, and the media gathered for a discussion of a variety of population issues, including immigration, infant mortality, birth control, family planning, and the education of women.

The document[1] endorses a new strategy which emphasizes the numerous linkages between population and development and focuses on meeting the needs of individual women and men rather than on achieving demographic targets.

Key to this new approach is empowering women and providing them with more choices through expanded access to education and health services and promoting skill development and employment. The Programme advocates making family planning universally available by 2015, or sooner, as part of a broadened approach to reproductive health and rights, provides estimates of the levels of national resources and international assistance that will be required, and calls on Governments to make these resources available.

The Programme of Action includes goals in regard to education, especially for girls, and for the further reduction of infant, child and maternal mortality levels. It also addresses issues relating to population, the environment and consumption patterns; the family; internal and international migration; prevention and control of the HIV/AIDS pandemic; information, education and communication; and technology, research and development.

Natural fertility

Natural fertility is a concept developed by French demographer Louis Henry to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control fertility, so that fertility depends only on physiological factors affecting fecundity. In contrast, populations that practice fertility control will have lower than "natural fertility" levels as a result of delaying first births (a lengthened interval between menarche and first pregnancy), spacing out the intervals between births, or stopping child-bearing at a certain age. Such control does not assume the use of artificial means of fertility regulation or modern contraceptive methods but can result from the use of traditional means of contraception or pregnancy prevention (e.g., coitus interruptus), or from social norms or practices regarding celibacy, the age at marriage and the timing and frequency of sexual intercourse, including periods of prescribed sexual abstinence. Ansley Coale and other demographers have developed several methods for measuring the extent of such fertility control, in which the idea of a natural level of fertility is an essential component.

Family economics

The family, although recognized as fundamental from Adam Smith on, received little systematic treatment in economics before the 1950s. A significant exception was Thomas Malthus's model of population growth. The work of Gary Becker and others initiated contemporary research with the application and extension of microeconomic theory and empirical methods. Standard aspects include:

* fertility and the demand for children in developed and developing countries[1][2]
* child health and mortality[3]
* interrelation of 'quantity' and 'quality' of children through investment of time and other resources of parents
* altruism in the family, including the rotten kid theorem[4]
* sexual division of labor through the household production function and outside the household.[5][6]
* mate selection,[7] search costs, marriage, divorce, and imperfect information[8]
* family background and opportunities of children.
* intergenerational mobility and inequality, including the bequest motive[9][10]
* human capital, social security, and the rise and fall of families.[11][12]

Geodemography

Geodemography includes the application or study of geodemographic classifications for business, social research and public policy but has a shorter history in academic research seeking to understand the processes by which settlements (notably, cities) evolve and neighborhoods are formed. It links the sciences of demography, the study of human population dynamics, geography, the study of the locational and spatial variation of both physical and human phenomena on Earth, [1] and also sociology.

The origins of geodemographics are often identified as Charles Booth and his studies of deprivation and poverty in early twentieth century London, and the Chicago School of sociology. Booth developed the idea of 'classifying neighborhoods', exemplified by his multivariate classification of the 1891 UK Census data to create a generalized social index of London’s (then) registration districts. Research at the Chicago School - though generally qualitative in nature - strengthened the idea that such classifications could be meaningful by developing the idea of ‘natural areas’ within cities: conceived as geographical units with populations of broadly homogenous social-economic and cultural characteristics.

The idea that census outputs could serve to identify and to characterize the geographies of cities gathered momentum with the increased availability of national census data and the computational ability to look for patterns in such data. Of particular importance to the emerging geodemographic industry was the development of clustering techniques to group statistically similar neighborhoods into classes on a 'like with like' basis. More recently, data have become available at finer geographical resolutions (such as postal units), often originating from private commercial (i.e. non-governmental) sources.

Commercial geodemographics emerged from the late 1970s with the launch of PRIZM by Claritas in the US and ACORN by CACI in the UK. Geodemography has been used to target consumer services to 'ideal' populations based on their lifestyle and location. These parameters have been taken from geographical databases as well as from electoral lists and credit agencies. Combining these builds a picture of the population characteristics in different locations. The geodemographic data that this provides can then be used by marketeers to target information towards those that they want to influence. This can be in the form of sales, services or even political information. At heart, geodemographics is just a structured method of making sense of complex socio-economic datasets.

In 2005 the Office for National Statistics (ONS) in collaboration with Dan Vickers and Phil Rees of the University of Leeds, released a free small scale social area classification of the UK[2] based on 2001 UK small area census data. Similar classifications had been developed for earlier censuses, notably by Stan Openshaw and colleagues at Newcastle and Leeds Universities, but access to these generally was restricted to the academic communities.

The 2005 Output Area Classification (OAC) of the UK is a move to 'open geodemographics' and reflects a concern that applications of commercial geodemographics in policy and social research can otherwise be 'black box': it is not always clear exactly what variables were used to classify small areas and to define their neighbourhood type, how those variables were weighted, or how similar (or otherwise) each of the neighbourhoods within a class type actually are. Open geodemographics provides such information (because it is not constrained by commercial interests) and is an important development for applied social research that also seeks to understand and to explain the roots causes or processes that generate aggregate spatial patterns of social behaviour and attitudes. The Output Area Classification is now supported by a user group [here].

Geodemographics has drawn critical attention. Some focus on the possible discriminatory and intrusive effects of geodemographic practices. Others wonder whether members of geodemographic groups really are sufficiently alike to be analysed together. The generally unknown variance within geodemographic groupings makes it difficult to assess the significance of trends found in data. This may not matter for commercial and service planning applications but is of some concern for public sector and social research. A way forward is to integrate geodemographics with more statistical frameworks of analysis, using multilevel methods for example.

Egg donation

Egg donation is the process by which a woman provides one or several eggs (ova, oocytes) for purposes of assisted reproduction or biomedical research. For assisted reproduction purposes, egg donation involves the process of in vitro fertilization as the eggs are fertilized in the laboratory. After the eggs have been obtained, the role of the egg donor is complete. Egg donation is part of the process of third party reproduction.

Indication

A need for egg donation may arise for a number of reasons. Infertile couples may resort to acquiring eggs through egg donation when the female partner cannot have genetic children because she may not have eggs that can be successfully fertilized. This situation is often based on advanced reproductive age. Early onset of menopause which can occur in women as early as their 20’s can require a woman to use donor eggs to grow her family. Some women are born without ovaries or other reproductive organs. Sometimes a woman's reproductive organs have been damaged due to disease or have been forced to have them surgically removed. Another indication would be a genetic disorder on part of the woman that can be circumvented by using eggs from another person. The couple can personally get acquainted with the egg donor, her children and family members. Or a couple can request an anonymous egg donor. Egg donation is also required for gay couples using surrogacy (see LGBT parenting).

* Congenital absence of eggs
o Turner syndrome [1]
o Gonadal dysgenesis/agenesis [1]

* Acquired reduced egg quantity / quality
o Oophorectomy[1]
o Premature menopause[1]
o Chemotherapy [1]
o Radiation therapy[1]
o Autoimmunity[1]
o Advanced maternal age [1]
o Compromised ovarian reserve [1]

* Other
o Diseases of X-Sex linkage[1]
o Repetitive fertilization or pregnancy failure [1]
o Ovaries inaccessible for egg retrieval [1]

Procedure
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Egg donors are recruited, screened, and give consent prior to participation in the IVF process. Some patients bring their own, designated donors, while other patients rely on the services of often anonymous donors typically recruited by egg donor agencies or, sometimes, IVF programs. Once the egg donor is recruited, she undergoes the IVF stimulation therapy, followed by the egg retrieval procedure. After retrieval, the ova are handed over to the recipient couple, fertilized by the sperm of the male partner in the laboratory, and after several days, the resulting embryo(s) is placed in the uterus of the recipient. For the embryo transfer the lining of the recipient has been appropriately prepared in a synchronous fashion. The recipient is usually the person who requested the service and then will carry and deliver the pregnancy and keep the baby.

Results

Results in treatments with the use of egg from donors often have a better than 50% chance of success. With egg donation, women who are past their reproductive years or menopause can become pregnant. The oldest woman thus to give birth is Adriana Iliescu, age 66. Babies born after egg donation are not genetically related to the recipient.

Donor motivation

An egg donor may be motivated by a number of reasons to provide eggs. Some egg donors may be altruistic and feel that participation in the reproductive process provides a benefit for another person, sometimes a person they know or are related to. Others may be attracted to the monetary compensation.

Risks

Egg donor

Egg donation carries risks for both donor and recipient. The egg donor may suffer complications from IVF, such as bleeding from the oocyte recovery procedure and reaction to the hormones used to induce hyperovulation (producing more than one egg), including ovarian hyperstimulation syndrome (OHSS) and, rarely, liver failure[2]. The long-term impact of egg donation on donors has not been well studied, but apparently some evidence suggests a risk of early menopause and increased risk of ovarian cancer[3].

According to Jansen and Tucker, writing in the same ART (assisted reproductive technologies) textbook referenced above[4], the risk of OHSS varies with the clinic administering the hormones, from 6.6 to 8.4% of cycles,half of them "severe." Patients treated with GnRH agonists appear to be at increased risk compared to those treated with GnRH antagonists. The most severe form of OHSS is life threatening. One study in the Netherlands found 10 documented cases of deaths from IVF, with a rate of 1:10,000. "All of these patients were treated with GnRH agonists and none of these cases have been published in the scientific literature." Hormone treatments that can be dangerous in the short-term may have long-term health effects.

Daniel Navot, writing in the same collection of reports states that mild OHSS is a sign that treatment is working and describes the symptoms of moderate OHSS as "includes significant ovarian englargement (5-12 cm)...abdominal pain, significant bloating,nausea, and diarrhea," symptoms attributable to ovarian enlargement and elevate estrogen levels. Signs that upgrade moderate OHSS to the severe form include liver dysfunction and anasarca. Criteia for severe OHSS include enlarge ovary, ascites, hemotacrit > 45%, WBC > 15,000, oliguria, creatinine 1.0-1.5 mg/dl, creatinine clearance > 50 ml/min, liver dysfunction, anasarca. Critical OHSS includes enlarged ovary, tense ascites with hydrothorax and pericardial effusion, hematocrit > 55%, WBC > 25,000, oligoanuria, creatinine > 1.6 mg/dl, creatinine clearance > 50 ml/min, renal failure, thromboembolic phenomena,ARDS.

Recipient

The recipient has the risk of contracting a transmittable disease. While the donor may test negative for HIV, such testing does not exclude the possibility that the donor has contracted HIV very recently, so the recipient faces a residual risk of exposure.

The recipient also trusts that the genetic and medical history of the donor is accurate. This factor of trust should not be underestimated in importance. Donors are paid thousands of dollars; monetary compensation may attract unscrupulous individuals inclined to conceal their true motivations. Moreover, recipients will have a de facto relationship to the biological parent of their offspring for life. Half of the child's genetic makeup, and related traits, capabilities, tendencies, etc. will come from the donor.

Multiple birth is a common complication if the physician transfers too many embryos. Incidence of twin births is very high.

Custody

Generally legal documents are signed to hand oocytes over to the recipient and renounce rights of ownership and custody on part of the donor, so that there will be no claims on part of the donor concerning the offspring.

Legality

Egg donation is regulated and /or prohibited in many countries. In the United States, having an attorney draft a contract is often necessary to establish and confirm the parental rights over any child.

Donor registries

A donor registry is a registry to facilitate donor conceived people, sperm donors and egg donors to establish contact with genetic kindred. They are mostly used by donor conceived people to find genetic half-siblings from the same egg- or sperm donor.

Some donors are non-anonymous, but most are anonymous, i.e. the donor conceived person doesn't know the true identity of the donor. Still, he/she may get the donor number from the fertility clinic. If that donor had donated before, then other donor conceived people with the same donor number are thus genetic half-siblings. In short, donor registries match people who type in the same donor number.

Alternatively, if the donor number isn't available, then known donor characteristics, e.g. hair, eye and skin color may be used in matching.

Donors may also register, and therefore, donor registries may also match donors with their genetic children.

References

1. ^ a b c d e f g h i j k l Womensinstiture
2. ^ Textbook of Assisted Reproductive Techniques, Laboratory and Clinical Perspectives, edited by David K. Gardner, 2001
3. ^ Kathryn Jean Lopez on Egg Selling on National Review Online
4. ^ Textbook of Assisted Reproductive Techniques, Laboratory and Clinical Perspectives, edited by David K. Gardner, 2001

ASRM Practice Committee Reports, Fertility Sterility 82, Suppl. 1, Sept. 2004.

See also

* Sperm donation
* Donor conceived people

External links

* Egg Donor Medications
* For Donors - Human Fertilisation and Embryology Authority UK
* Fertility Stories - Stories of couples using egg donation and of women who have chosen to become egg donors
* Parents Via Egg Donation Organization was created to provide an informational and supportive environment where parents and parents-to-be can come together to exchange information about all facets of the egg donation process with respect to growing their families.

Sperm donation

Sperm donation is the name of the practice by which a man, known as a sperm donor, provides his semen with the intention that it be used to produce a baby where the man does not have sexual relations with the recipient of his semen. Attempts are made to impregnate a woman with the donor's sperm using third party reproduction techniques notably artificial insemination.

A sperm donor may donate his sperm directly to the woman recipient, or he may donate it at a clinic known as a sperm bank.

Sperm donation commonly assists couples unable to produce children because of 'male factor' fertility problems,[citation needed] but it is increasingly used as a means to enable single women and single and coupled lesbians to have their own children.[citation needed] The sperm donor is the genetic or biological father of each child produced with the use of his sperm. When a donor's sperm is successfully used repeatedly for impregnation, numbers of siblings and half-siblings will be produced.

Donors may be either anonymous or non-anonymous, although laws may require donors to be one or the other, or restrict the number of children each donor may father. Although many donors choose to remain anonymous, new technologies such as the internet and DNA technology has opened up new avenues for those wishing to know more about the biological father, siblings and half-siblings.

Process

When a sperm donor provides his sperm through a sperm bank or fertility clinic he will usually enter into a contract to donate sperm for a specified contractual minimum period of time ranging from six to twenty four months. To donate sperm a man must generally meet specific requirements regarding age and medical history. In the United States, sperm banks are regulated as Human Cell and Tissue or Cell and Tissue Bank Product (HCT/Ps) establishments by the FDA. Many states also have regulations in addition to those imposed by the FDA. A man generally donates sperm at a clinic or sperm bank by way of masturbation in a private room or cabin, known as a 'men's production room' (UK) or a 'masturbatorium' (USA). Many of these facilities contain pornography such as videos, magazines, and/or photographs in order to assist the donor to produce the ejaculate.

Types of donors

General
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Many sperm donors donate their sperm for purely altruistic reasons so that childless women or couples may produce their own children.[citation needed] Where such donations are through a sperm bank, the sperm bank will generally re-imburse the donor his reasonable expenses.[citation needed]

Some sperm donors may however, seek financial compensation, particularly those who supply sperm samples to order at specific times and at a specific sperm bank on a regular basis for what may be many months, in the knowledge that these samples will be used to produce a number of pregnancies. Many sperm banks therefore offer financial rewards which more adequately compensate for such a commitment.[citation needed] A sperm donor will rarely, if ever, know the exact number of pregnancies which his samples have produced, and indeed, an accurate or exact figure very often will not exist.[citation needed]

In the past sperm banks were keen to recruit as sperm donors men who had already fathered children. However, with the advances of microbiology, sperm can readily be checked for its fecundity, and sperm banks will now rely upon their own tests to ensure the quality of sperm.

Sperm donors are required to be fit and healthy and generally their 'sperm count' will be well above average to ensure that pregnancies may be easily and swiftly achieved by the use of their sperm. Sperm banks impose age restrictions on donors, usually from 18 to 40 or 45, but in practice the majority of donors are young men who are often college students.[citation needed]

Donated sperm may be prepared for use by artificial insemination in intrauterine insemination (ICI) or intra-cervical insemination (ICI), or it may be prepared for use through other assisted reproduction techniques (ART). Donated sperm may also be used in surrogacy arrangements and for producing embryos with donated eggs for implanting in a woman who is not genetically related to the child she produces and who may or may not be a surrogate.

Sperm banks maintain lists or catalogues of donors which provide basic information about the donor such as racial origin, height, weight, colour of eyes, blood group etc. Some of these catalogues are available for browsing via the internet, whilst others are only made available to patients when they apply to a sperm bank for treatment. Some sperm banks make additional information about each donor available for an additional fee, and others make additional basic information known to children prodcued from donors when those children reach the age of eighteen. Some clinics offer 'exclusive donors' whose sperm is only used to produce pregnancies for one recipient woman. How accurate this is, or can be, is not known, and neither is it known whether the information produced by sperm banks, or by the donors themseles, is true. Many sperm banks will, however carry out whatever checks they can to verify the information they request, such as checking the identity of the donor and contacting his own doctor to verify medical details. Simply because such information is not verifiable does not imply that it is in any way inaccurate, and a sperm bank will rely upon its reputation which, in turn, will be based upon its success rate and upon the accuracy of the information about its donors which it makes available.

Anonymous or non-anonymous

Anonymous sperm donation is where the child and/or receiving couple will never get to know the identity of the donor, and non-anonymous when they will.

A donor who makes a non-anonymous sperm donation is termed a known donor.

Anonymous

Most sperm donors are anonymous, i.e. the clinic will never give contact information of the receiving woman/couple and the woman/couple will not be told the identity of the donor. However some information about the donor may be released to the woman/couple. A limited donor information at most includes height, weight, eye, skin and hair colour. In Sweden, this is all the information a receiver gets. In the US, on the other hand, additional information may be given, such as a comprehensive biography and sound/video samples.

The law usually protects sperm donors from being responsible for children produced from their donations, and the law also usually provides that sperm donors have no rights over the children which they produce.

Non-anonymous

Several countries, e.g. Sweden, Norway, the Netherlands, Britain, Switzerland, Australia[1] and New Zealand only allow non-anonymous sperm donation. The child may, when grown up (15-18 years old), get contact information from the sperm bank about his/her biological father. In Denmark, however, a sperm donor may choose to be either anonymous or non-anonymous. Nevertheless, the initial information which the receiving woman/couple will receive is the same. In the United States, sperm banks are permitted to disclose the identity of a non-anonymous donor to any children brought to the world by that donor, once the child turns 18.[2]

Private donors

Besides the men who donate to a sperm bank there are also less institutional donations. For example, mother may approach a friend, or may obtain a "private" donor by advertising. A number of web sites seek to link such donors and donees, while advertisements in same sex publications are not uncommon. Although artificial insemination is usually used, frozen sperm need not be. Most such donors meet the donees and are therefore usually known to the recipient. Private donations are usually free - avoiding the significant costs of a more medicalised insemination - and theoretically, where fresh rather than frozen semen is used the chances of pregnancy may be higher. Against this are the usually higher risks of disease transmission and the risk of a legal dispute regarding access or maintenance. The laws of some nations (e.g. New Zealand), allow for recognition of written agreements between donors and donees in a similar way to institutional donations. In others, e.g. Sweden[3], this is not guaranteed.

Limitation

Where a sperm donor donates sperm through a sperm bank, the sperm bank will generally undertake a number of medical and scientific checks to ensure that the donor produces sperm of sufficient quantity and quality and that the donor is healthy and will not pass diseases through the use of his sperm. The donor's sperm must also withstand the freezing and thawing process necessary to store and quarantine the sperm. The cost to the sperm bank for such tests is not inconsiderable. This normally means that clinics may use the same donor to produce a number of pregnancies in a number of different women.

A sperm donor generally enters into an agreement with the sperm bank to supply sperm usually once a week for a period of between four months and two years, depending on the extent to which the sperm may be used to produce the maximum number of pregnancies permitted (if any)(but see also below, "Onselling"). A single donation (i.e. one ejaculate) prepared into samples for intra-cervical use (ICI) or a donation prepared into 'washed' samples for intrauterine insemination (IUI) will enable each sample to have about the same chance of producing a pregnancy as sperm delivered through sexual intercourse (i.e. a rate of btween 7 and 20% depending on a number of factors). Samples prepared for other ART uses may allow more pregnancies to be produced from one donation. A single donation prepared into samples for IVF for example, may be sufficient to fertilise up to eight batches of eggs. The success rate for embryos subsequently implanted in a woman is approximately between 20 and 45% per treatment cycle (see assisted reproduction). 'Washed' or 'unwashed' samples may also be used for ICSI thus increasing the number of pregnancies produced from a single donation.

The number of children permitted to be born from a single donor varies according to law and practice. Laws vary from state to state, and a sperm bank may also impose its own limits. The latter will be based on the reports of pregnancies which the sperm bank receives, although this relies upon the accuracy of the returns and the actual number of pregnancies may therefore be somewhat higher. Nevertheless, sperm banks frequently impose a lower limit on geographical numbers than some US states and may also limit the overall number of pregnancies which are permitted from a single donor. When calculating the numbers of children born from each donor, the number of siblings produced in any 'family' as a result of sperm donation from the same donor are almost always excluded (but see below for the provisions in various states). There is, of course, no limit to the number of offspring which may be produced from a single donor where he supplies his sperm privately.

Where a limit on the number of offspring which are allowed to be produced from each donor is imposed, this is usually in order to reduce the chance of consanguinity by the half-siblings of the donor. However, some donors may produce substantial numbers of offspring, particularly where they donate through different clinics, where sperm is onsold or is exported to different jurisdictions, and where countries or states do not have a central register of donors.

Sperm banks frequently publish their 'pregnancy rates' which are success rates according to the number of pregnancies achieved as a percentage of the total number of treatments provided. Sperm banks may also publish 'birth rates' giving the number of live births as a percentage of treatment cycles. These rates vary from clinic to clinic, according to the method of insemination or ART used and of the ages of the recipients. Sperm from a sperm donor may be used by a clinic until the maximum number (if any) of live births in each case has been achieved.

Sperm may also be donated through an agency rather than through a sperm bank. The agency recruits sperm donors, usually via the internet, and it also advertises its services on the internet. Donors undergo the same kind of checks and tests required by a sperm bank. However, in the case of an agency, the sperm will be supplied to the recipient woman fresh rather than frozen. A woman chooses a donor and notifies the agency when she requires donations. The agency notifies the donor who supplies his sperm on the appropriate days in a container provided by the agency. This is collected and delivered by courier and the woman uses the donor's sperm to perform her own insemination. The whole process preserves the anonymity of the parties but it is largely unregulated and, because the sperm is not quarantined, it carries risks which are not associated with sperm banks. Donors providing sperm in this way will not be protected by laws which apply to donations through a sperm bank or fertility clinic and will, if traced, be regarded as the legal father of each child produced by their sperm. In addition, agencies rarely impose or enforce limits on the numbers of children which may be produced by a particular donor.

Onselling

There is a market for vials of processed sperm and for various reasons a sperm bank may sell on stocks of vials which it holds (known as 'onselling'). Onselling therefore enables a sperm bank to maximize the sale and disposal of sperm samples which it has processed. The reasons for onselling may be where part of, or even the main business of, a particular sperm bank is to process and store sperm rather than to use it in fertility treatments, or where a sperm bank is able to collect and store more sperm than it can use within nationally set limits. In the latter case a sperm bank may sell on sperm from a particular donor for use in another jurisdiction after the number of pregnancies achieved from that donor has reached its national maximum..

A UK sperm bank however, may only onsell sperm before the national limit of ten families has been achieved from one donor within the UK. This means, for example, that a sperm bank may recruit a donor and prepare samples for ICI, IUI and ART use from his donations. After 9 months it is able to release the 10 or so samples donated within the first 3 months, from 6 month quarantine ( approximately 100 vials) and it uses these to achieve 6 pregnancies (although more pregnancies could, of course, be achieved from the number of vials prepared as illustrated). The sperm bank is then able to onsell sperm from that donor to sperm banks and clinics outside the UK and it can illustrate the fecundity of the various types of samples it sells. The donor may continue to donate for several years (usually 3 or 4) and the UK clinic will be able to achieve a further 4 pregnancies in the UK at the end of that period within the UK rules. It will also continue to hold stocks of that donor's sperm for sibling use after that time. The donor must however, have agreed to the export and to the use of his donations abroad, and he must be told that reguations for use outside the UK will vary. He must not have put a limit on the number of births which may be achieved from his donations. The HFEA must be notified of exports of sperm from the UK but it does not limit these since it is only concerned with the storage and use of sperm within the UK.

Emrbyos may also be onsold. In the case of the UK, because the embryo wll have been created in the UK under a regulated process, the consent of the HFEA must be obtained if these are to be exported.

Onselling is normally only appropriate where the donor remains anonymous. Sperm banks purchasing sperm samples may in turn onsell these to other sperm banks. Onselling may therefore give rise to numerous pregnancies being produced from individual donors, but in every case rules as to use and the limitation on the number of pregnacies which apply locally will reduce the risk of consanguinity. The lack of overall records as to use and success will mean that the numbers of pregnancies achieved from the samples of an individual donor will not exist and the donor will not be at risk of knowing the large number of births that were produced from the samples he donated.

Sperm may also be sold on for research or educational purposes, usually after the number of births from the donor concerned has reached its maximum. Sperm is used for genetic and fertility testing, and also for research into birth control.

Donor tracking

Even when the donor had chosen to be anonymous, there are still opportunities to find the biological father for curious people conceived by donor sperm. Registries and DNA-databases are useful for this purpose.

Tracking by registries

Some donors are non-anonymous, but most are anonymous, i.e. the donor conceived person doesn't know the true identity of the donor. Still, he/she may get the donor number from the fertility clinic. If that donor had donated before, then other donor conceived people with the same donor number are thus genetic half-siblings. In short, donor registries matches people who type in the same donor number.

Tracking by DNA-databases

However, even sperm donors who have not initiated contact through a registry are now increasingly being traced by their offspring. In the current era there can be no such thing as guaranteed anonymity. Through the advent of DNA testing and internet access to extensive databases of information, one sperm donor has recently been traced. In 2005 it was revealed in New Scientist magazine[4] that an enterprising 15-year-old used information from a DNA test and the internet to identify and contact his genetic father, who was a sperm donor. This has brought into question the ability of sperm donors to stay anonymous.

Payment

The majority of sperm donors who donate their sperm through a sperm bank receive some kind of payment. This varies from the situation in the United Kingdom where donors are only entitled to their expenses in connection with the donation, to the situation with some US sperm banks where a donor receives a set fee for each donation plus an additional amount for each vial stored. Whilst the amounts concerned in each case are not excessive, some donors are known to donate to more than one sperm bank every week and they are thus able to secure a reasonable monthly income.

Some private donors may seek remuneration although the majority of these donate for altruistic reasons. Equipment to collect, freeze and store sperm is available to the public notably through certain US outlets, and some donors process and store their own sperm which they then sell via the internet.

The selling price of processed and stored sperm is considerably more than the sums which are received by donors. Treatments with donor sperm are generally expensive and are seldom available free of charge through national health services. Sperm banks often package treatments into eg three cycles, and in cases of IVF or other ART treatments, they may reduce the charge if a patient donates any spare embryos which are produced through the treatment. There is often more demand for fertiltity treatment with donor sperm than there is donor sperm available, and this has the effect of keeping the cost of such treatments reasonably high.

International comparison

On the global market, Denmark has a well developed system of sperm export. This success mainly comes from the reputation of Danish sperm donors for being of high quality and, in contrast with the law in the other Nordic countries, gives donors the choice to remain anonymous to the receiving couple.[5] However, they supply non-anonymous samples as well. More than 50 countries worldwide are importers, including Paraguay, Canada, Kenya and Hong Kong.[5] However, the Food and Drug Administration (FDA) of the US has banned import of any sperm, motivated by a risk of mad cow disease.[6]

Sperm bank

A sperm bank or cryobank is a facility that collects and stores human sperm mainly from sperm donors, primarily for the purpose of achieving pregnancies through third party reproduction, notably by artificial insemination. The first two sperm banks were opened in Iowa City, Iowa, USA and Tokyo, Japan in 1965.[citation needed]


Services

Storage

The sperm is stored in small vials or straws of holding between 0.4 and 1.0 ml and cryogenically preserved in liquid nitrogen tanks. There seems to be no limit on how long frozen sperm can be stored, and a baby has been conceived in the UK using sperm frozen for 21 years[1]. Before freezing, sperm may be prepared so that it can be used for intra-cervical insemination (ICI), intra-uterine insemination (IUI) or for IVF(or assisted reproduction) (ART).

Use

Sperm supplied by a sperm bank may be used where a woman's partner is infertile or where he carries genetic disease. Increasingly, donor sperm is used to achieve a pregnancy where a woman has no male partner, including a rising percentage of single or coupled lesbians. Sperm from a sperm donor may also be used in surrogacy arrangements and for creating embryos for embryo donation. Donor sperm may be supplied by the sperm bank directly to the recipient to enable a woman to perform her own artificial insemination or, more usually, to a woman through a registered medical practitioner who will perform an appropriate method of insemination or IVF treatment using the donor sperm in order for the woman to become pregnant.

Sperm banks may supply other sperm banks or a fertility clinic with donor sperm to be used for achieving pregnancies. Sperm banks may also supply sperm for research or educational purposes.

In countries where sperm banks are allowed to operate, the sperm donor will not usually become the legal father of the children he produces as the result of the use of the sperm he donates, but he will be the 'biological father' of such children. In cases of surrogacy involving embryo donation, a form of 'gestational surrogacy', the 'commissioning mother' or the 'commissioning parents' will not be biologically related to the child and may need to go through an adoption procedure.

As with other forms of third party reproduction, the use of donor sperm from a sperm bank gives rise to a number of moral, legal and ethical issues.

Men may also use a sperm bank to store their own sperm for future use particularly where they anticipate traveling to a war zone or having to undergo chemotherapy which might damage the testes.

Selection

Sperm banks make information available about the sperm donors whose donations they hold in the sperm bank to enable customers to select the donor whose sperm they wish to use. This information is often available by way of an on-line catalog. A sperm bank will also usually have facilities to help customers to make their choice and they will be able to advise on the suitablitity of donors for individual donors and their partners.

Where the recipient woman has a male partner she may prefer to use sperm from a donor whose physical features are similar to those of her partner. In many cases, the choice of a donor with the correct blood group will be paramount with particular considerations involving the use of sperm from donors with negative blood groups. If a surrogate is to be used, such as where the customer is not intending to carry the child, considerations about her blood group etc will also need to be taken into account. Information made available by a sperm bank will usually include the race, height, weight, blood group, health and eye colour of the donor. Sometimes information about his age, family history and educational achievements will also be given. Some sperm banks make a 'personal profile' of a donor available and occasionally more information may be purchased about a donor, either in the form of a DVD or in written form. Catalogs usually state whether samples supplied in respect of a particular donor have already given rise to pregnancies, but this is not necessarily a guide to the fecundity of the sperm since a donor may not have been in the program long enough for any pregnancies to have been recorded.

The catalog will also state whether samples of sperm are available for ICI, IUI and/or ART use. IUI and ART are 'washed' samples, ART samples being those prepared exclusively for IVF use and containing a concentration of highly motile sperm which are fewer in number than those in other vials.

Sperm banks may also allow people to choose the sex of their child or to choose what characteristics they want their child or children to inherit. This is an example of selective breeding.

Regulation

In the United States sperm banks are regulated by the FDA with new guidelines in effect May 25, 2005. There are also regulation in different states including New York and California. In the EU the sperm banks are regulated by the EU Tissue Directive in effect April 7, 2006.

Selection and screening of donors

Using anonymous donor sperm or sperm from a known or identifiable sperm donor through a sperm bank is a safe and reliable method of achieving a pregnancy. A sperm bank takes a number of steps to ensure the health and quality of the sperm which it supplies and it will inform customers of the checks which it undertakes, providing relevant information about individual donors. A sperm bank recruits donors via advertising, often in colleges and in local newspapers, and also via the internet. A donor must be a fit healthy male who is willing to undergo frequent and rigorous testing and who is willing to donate his sperm so that it can be used to impregnate women who are unrelated to, and unknown by, him. The donor will produce the sperm at the sperm bank and the sperm will be checked to ensure fecundity and to ensure that motile sperm survive the freezing process. In addition, donors are tested and constantly re-tested and monitored and their identity is required to be proven. All sperm is frozen and stored for a minimum of 6 months before being released for sale to ensure that the donor is healthy and that his sperm will not pass any sexual or other transmissable diseases to the recipient. Donors are subject to tests for diseases such as human immunoviruses HIV (HIV-1 and HIV-2), human T-cell lymphotropic viruses (HTLV-1 and HTLV-2), syphilis, chlamydia, gonorrhea, Hepatitis B virus, Hepatitis C virus, cytomegalovirus (CMV), cystic fibrosis, Karyotyping 46[2] [3] XY, and transmissible spongiform encephalopathy or Creutzfeldt-Jakob disease. Karyotyping is not a requirement in the U.S. but some sperm banks choose to test donors as an extra service to the customer.[4] A sperm donor may also be subject to genetic testing and a sperm bank will obtain medical records of the sperm donor and his family, often for several generations. A sperm sample is usually tested micro-biologically at the sperm bank before it is prepared for freezing and subsequent use. A sperm donor's blood group is also tested to ensure compatibility with the recipient.

Fertility clinic

Fertility clinics are staffed medical clinics that assist couples, and sometimes individuals, who want to become parents but for medical reasons have been unable to achieve this goal via the natural course. Clinics apply a number of tests and sometimes very advanced medical procedures to obtain the desired conceptions and pregnancies.

For the male, semen collection is a standard diagnostic test to ascertain problems with the semen quality. In vitro fertilisation is one common assisted reproductive technology procedure performed at a fertility clinic.

Birth control

Birth control, sometimes synonymous with contraception, is a regimen of one or more actions, devices, or medications followed in order to deliberately prevent or reduce the likelihood of pregnancy or childbirth. "Contraception" may refer specifically to mechanisms that are intended to reduce the likelihood of a sperm cell fertilizing the egg. Birth control is commonly used as part of family planning.

The history of birth control began with the discovery of the connection between coitus and pregnancy. The oldest forms of birth control included coitus interruptus, pessaries, and the ingestion of herbs that were believed to be contraceptive or abortifacient. The earliest record of birth control use is an Ancient Egyptian set of instructions on creating a contraceptive pessary.

Different methods of birth control have varying characteristics. Condoms, for example, are the only methods that provide significant protection from sexually transmitted diseases. Cultural and religious attitudes on birth control vary significantly.

History

Probably the oldest methods of contraception (aside from sexual abstinence) are coitus interruptus, lactational, certain barrier methods, and herbal methods (emmenagogues and abortifacients).

Coitus interruptus (withdrawal of the penis from the vagina prior to ejaculation) probably predates any other form of birth control. Once the relationship between the emission of semen into the vagina and pregnancy was known or suspected, some men began to use this technique. This is not a particularly reliable method of contraception, as few men have the self-control to correctly practice the method at every single act of sexual intercourse.[1] Although it is commonly believed that pre-ejaculate fluid can cause pregnancy, modern research has shown that pre-ejaculate fluid does not contain viable sperm.[2][3]

There are historic records of Egyptian women using a pessary (a vaginal suppository) made of various acidic substances and lubricated with honey or oil, which may have been somewhat effective at killing sperm.[4] However, it is important to note that the sperm cell was not discovered until Anton van Leeuwenhoek invented the microscope in the late 17th century, so barrier methods employed prior to that time could not know of the details of conception. Asian women may have used oiled paper as a cervical cap, and Europeans may have used beeswax for this purpose. The condom appeared sometime in the 17th century, initially made of a length of animal intestine. It was not particularly popular, nor as effective as modern latex condoms, but was employed both as a means of contraception and in the hopes of avoiding syphilis, which was greatly feared and devastating prior to the discovery of antibiotic drugs.

Various abortifacients have been used throughout human history. Some of them were effective, some were not; those that were most effective also had major side effects. One abortifacient reported to have low levels of side effects — silphium — was harvested to extinction around the 1st century.[5] The ingestion of certain poisons by the female can disrupt the reproductive system; women have drunk solutions containing mercury, arsenic, or other toxic substances for this purpose. The Greek gynaecologist Soranus in the 2nd century suggested that women drink water that blacksmiths had used to cool metal. The herbs tansy and pennyroyal are well-known in folklore as abortive agents, but these also "work" by poisoning the woman. Levels of the active chemicals in these herbs that will induce a miscarriage are high enough to perilously damage the liver, kidneys, and other organs. However, in those times where risk of maternal death from postpartum complications was high, the risks and side effects of toxic medicines may have seemed less onerous. Some herbalists claim that black cohosh tea will also be effective in certain cases as an abortifacient.[6]

Aside from abortifacients, herbal contraceptives in folklore have also included a few preventative measures. Hibiscus rosa-sinensis, known in Ayurveda as a contraceptive, may have antiestrogenic properties.[7] Papaya seeds, rumored to be a male contraceptive, have recently been studied for their azoospermic effect on monkeys.[8]

The fact that various effective methods of birth control were known in the ancient world sharply contrasts with a seeming ignorance of these methods in wide segments of the population of early modern Christian Europe. This ignorance continued far into the 20th century, and was paralleled by eminently high birth rates in European countries during the 18th and 19th centuries.[9] Some historians have attributed this to a series of coercive measures enacted by the emerging modern state, in an effort to repopulate Europe after the population catastrophe of the Black Death, starting in 1348. According to this view, the witch hunts were the first measure the modern state took in an attempt to eliminate knowledge about birth control within the population, and monopolize it in the hands of state-employed male medical specialists (gynecologists). Prior to the witch hunts, male specialists were unheard of, because birth control was naturally a female domain.[10]

Presenters at a family planning conference told a tale of Arab traders inserting small stones into the uteruses of their camels in order to prevent pregnancy, a concept very similar to the modern IUD. Although the story has been repeated as truth, it has no basis in history and was meant only for entertainment purposes.[11] The first interuterine devices (which occupied both the vagina and the uterus) were first marketed around 1900. The first modern intrauterine device (contained entirely in the uterus) was described in a German publication in 1909. The Gräfenberg ring, the first IUD that was used by a significant number of women, was introduced in 1928.[12]

The rhythm method (with a rather high method failure rate of ten percent per year) was developed in the early 20th century, as researchers discovered that a woman only ovulates once per menstrual cycle. Not until the 1950s, when scientists better understood the functioning of the menstrual cycle and the hormones that controlled it, were methods of hormonal contraception and modern methods of fertility awareness (also called natural family planning) developed.

Margaret Sanger was an American birth control activist and the founder of the American Birth Control League (which eventually became Planned Parenthood). She was instrumental in opening the way to access birth control.

In 1960 the FDA approved the first form of hormonal birth control, the combined oral contraceptive pill.

Recently, due to a legislative error in the U.S. Deficit Reduction Act of 2005 (implemented in January 2007) college health centers and many safety net health care providers have been cut out of the drug pricing discount program, which formerly allowed contraceptives to be sold to students and women of low income in the United States at low cost. As a result, 3 million college students and hundreds of thousands of low-income women have lost access to affordable birth control.[ citation needed ] The Prevention Through Affordable Access Act (SR 2347 / HR 4054) has been introduced[ when? ] into Congress to correct the error, however as of August 2008 had not been seen on the floor.

Methods

Physical methods


Physical methods may work in a variety of ways, among them: physically preventing sperm from entering the female reproductive tract; hormonally preventing ovulation from occurring; making the woman's reproductive tract inhospitable to sperm; or surgically altering the male or female reproductive tract to induce sterility. Some methods use more than one mechanism. Physical methods vary in simplicity, convenience and efficacy.

Barrier methods place a physical impediment to the movement of sperm into the female reproductive tract.

Condom (rolled-up).

The most popular barrier method is the male condom, a latex or polyurethane sheath placed over the penis. The condom is also available in a female version, which is made of polyurethane. The female condom has a flexible ring at each end — one secures behind the pubic bone to hold the condom in place, while the other ring stays outside the vagina.

Cervical barriers are devices that are contained completely within the vagina. The contraceptive sponge has a depression to hold it in place over the cervix. The cervical cap is the smallest cervical barrier. Depending on the type of cap, it stays in place by suction to the cervix or to the vaginal walls. The diaphragm fits into place behind the woman's pubic bone and has a firm but flexible ring, which helps it press against the vaginal walls.

Spermicide may be placed in the vagina before intercourse and creates a chemical barrier. Spermicide may be used alone, or in combination with a physical barrier.

There are variety of delivery methods for hormonal contraception.

Ortho Tri-cyclen, a brand of oral contraceptive, in a dial dispenser.

Combinations of synthetic oestrogens and progestins (synthetic progestogens) are commonly used. These include the combined oral contraceptive pill ("The Pill"), the Patch, and the contraceptive vaginal ring ("NuvaRing"). Not currently available for sale in the United States is Lunelle, a monthly injection.

Other methods contain only a progestin (a synthetic progestogen). These include the progesterone only pill (the POP or 'minipill'), the injectables Depo Provera (a depot formulation of medroxyprogesterone acetate given as an intramuscular injection every three months) and Noristerat (Norethindrone acetate given as an intramuscular injection every 8 weeks), and contraceptive implants. The progestin-only pill must be taken at more precisely remembered times each day than combined pills. The first contraceptive implant, the original 6-capsule Norplant, was removed from the market in the United States in 1999, though a newer single-rod implant called Implanon was approved for sale in the United States on July 17, 2006. The various progestin-only methods may cause irregular bleeding during use.

Ormeloxifene (Centchroman)

Ormeloxifene (Centchroman) is a selective oestrogen receptor modulator, or SERM. It causes ovulation to occur asynchronously with the formation of the uterine lining, preventing implantation of a zygote. It has been widely available as a birth control method in India since the early 1990s, marketed under the trade name Saheli. Centchroman is legally available only in India.

Emergency contraception

Some combined pills and POPs may be taken in high doses to prevent pregnancy after a birth control failure (such as a condom breaking) or after unprotected sex. Hormonal emergency contraception is also known as the "morning after pill," although it is licensed for use up to three days after intercourse.

Copper intrauterine devices may also be used as emergency contraception. For this use, they must be inserted within five days of the birth control failure or unprotected intercourse.

Emergency contraception appears to work by suppressing ovulation.[13][14] However, because it might prevent a fertilized egg from implanting, some people consider it a form of abortion. The details of the possible methods of action are still being studied.

An intrauterine device.

These are contraceptive devices which are placed inside the uterus. They are usually shaped like a "T" — the arms of the T hold the device in place. There are two main types of intrauterine contraceptives: those that contain copper (which has a spermicidal effect), and those that release a progestogen (in the US the term progestin is used).

The terminology used for these devices differs in the United Kingdom and the United States. In the US, all devices which are placed in the uterus to prevent pregnancy are referred to as intra-uterine devices (IUDs) or intra-uterine contraceptive devices (IUCDs). In the UK, only copper-containing devices are called IUDs (or IUCDs), and hormonal intrauterine contraceptives are referred to with the term Intra-Uterine System (IUS). This may be because there are seven types of copper IUDs available in the UK, compared to only one in the US.

Induced abortion

Abortion can be done with surgical methods, usually suction-aspiration abortion (in the first trimester) or dilation and evacuation (in the second trimester). Medical abortion uses drugs to end a pregnancy and is approved for pregnancies where the length of gestation has not exceeded 8 weeks.

Some herbs are believed to cause abortion (abortifacients). The efficacy of these plants as such has never been studied in humans. Some animal studies have found them to be effective on other species.[15][6] The use of herbs to induce abortion is not recommended due to the risk of serious side effects.

Abortion is subject to ethical debate.

Sterilization

Surgical sterilization is available in the form of tubal ligation for women and vasectomy for men. In women, the process may be referred to as "tying the tubes," but the fallopian tubes may be tied, cut, clamped, or blocked. This serves to prevent sperm from joining the unfertilized egg. The non-surgical sterilization procedure, Essure, is an example of a procedure that blocks the tubes. Sterilization should be considered permanent.

Behavioral methods

Behavioral methods involve regulating the timing or methods of intercourse to prevent the introduction of sperm into the female reproductive tract, either altogether or when an egg may be present.

Fertility awareness

Symptoms-based methods of fertility awareness involve a woman's observation and charting of her body's fertility signs, to determine the fertile and infertile phases of her cycle. Most methods track one or more of the three primary fertility signs:[16] changes in basal body temperature, in cervical mucus, and in cervical position. If a woman tracks both basal body temperature and another primary sign, the method is referred to as symptothermal. Some fertility monitoring devices use urinalysis to follow the levels of estrogen and luteinizing hormone throughout a woman's menstrual cycle. Other bodily cues such as mittelschmerz are considered secondary indicators.

Calendar-based methods such as the rhythm method and Standard Days Method are dissimilar from symptoms-based fertility awareness methods, in that they do not involve the observation or recording of bodily cues of fertility. Instead, calendar-based methods estimate the likelihood of fertility based on the length of past menstrual cycles. These methods are less accurate than symptoms-based fertility awareness methods, and are considered by many fertility awareness teachers to have been obsolete for at least 20 years.

Charting of the menstrual cycle may be done by the woman on paper or with the assistance of software. The calendar-based methods may use a device such as CycleBeads. Symptoms-based methods may be assisted by fertility monitoring devices that accept and interpret temperature readings, information from home urinalysis tests, or both. To avoid pregnancy with fertility awareness, unprotected sex is restricted to the least fertile period. During the most fertile period, barrier methods may be availed, or she may abstain from intercourse.

The term natural family planning (NFP) is sometimes used to refer to any use of FA methods. However, this term specifically refers to the practices which are permitted by the Roman Catholic Church — breastfeeding infertility, and periodic abstinence during fertile times. FA methods may be used by NFP users to identify these fertile times.

Coitus interruptus

Coitus interruptus (literally "interrupted sex"), also known as the withdrawal method, is the practice of ending sexual intercourse ("pulling out") before ejaculation. The main risk of coitus interruptus is that the man may not perform the maneuver correctly, or may not perform the maneuver in a timely manner. Although concern has been raised about the risk of pregnancy from sperm in pre-ejaculate, several small studies[2][3] have failed to find any viable sperm in the fluid.

Avoiding vaginal intercourse

The risk of pregnancy from non-vaginal sex, such as outercourse (sex without penetration), anal sex, or oral sex is virtually zero. (A very small risk comes from the possibility of semen leaking onto the vulva (with anal sex) or coming into contact with an object, such as a hand, that later contacts the vulva.)

Abstinence

Sexual abstinence is the practice of refraining from all sexual activity.

Lactational

Most breastfeeding women have a period of infertility after the birth of their child. The lactational amenorrhea method, or LAM, gives guidelines for determining the length of a woman's period of breastfeeding infertility.

Methods in development

For females

* Praneem is a polyherbal vaginal tablet being studied as a spermicide, and a microbicide active against HIV.[17]
* BufferGel is a spermicidal gel being studied as a microbicide active against HIV.[18]
* Duet is a disposable diaphragm in development that will be pre-filled with BufferGel.[19] It is designed to deliver microbicide to both the cervix and vagina. Unlike currently available diaphragms, the Duet will be manufactured in only one size and will not require a prescription, fitting, or a visit to a doctor.[18]
* The SILCS diaphragm is a silicone barrier which is still in clinical testing. It has a finger cup molded on one end for easy removal. Like the Duet, the SILCS is novel in that it will only be available in one size.
* A vaginal ring is being developed that releases both estrogen and progesterone, and is effective for over 12 months.[20]
* Two types of progestogen-only vaginal rings are being developed. Progestogen-only products may be particularly useful for women who are breastfeeding.[20] The rings may be used for four months at a time.[21]
* A progesterone-only contraceptive is being developed that would be sprayed onto the skin once a day.[22]
* Quinacrine sterilization and the Adiana procedure are two permanent methods of birth control being developed.[23]

For males

Other than condoms and withdrawal, there are currently no available methods of reversible contraception which males can use or control. Several methods are in research and development:

* As of 2007, a chemical called Adjudin is currently in Phase II human trials as a male oral contraceptive.[24]

* RISUG (Reversible Inhibition of Sperm Under Guidance), is an experimental injection into the vas deferens that coats the walls of the vas with a spermicidal substance. The method can potentially be reversed by washing out the vas deferens with a second injection.

* Experiments in vas-occlusive contraception involve an implant placed in the vasa deferentia.

* Experiments in heat-based contraception involve heating a man's testicles to a high temperature for a short period of time.

Misconceptions

Modern misconceptions and urban legends have given rise to a great deal of false claims:

* The suggestion that douching with any substance immediately following intercourse works as a contraceptive is untrue. While it may seem like a sensible idea to try to wash the ejaculate out of the vagina, it is not likely to be effective. Due to the nature of the fluids and the structure of the female reproductive tract, douching most likely actually spreads semen further towards the uterus. Some slight spermicidal effect may occur if the douche solution is particularly acidic, but overall it is not scientifically observed to be a reliably effective method.
* It is a myth that a female cannot become pregnant as a result of the first time she engages in sexual intercourse.
* While women are usually less fertile for the first few days of menstruation,[25] it is a myth that a woman absolutely cannot get pregnant if she has sex during her period.
* Having sex in a hot tub does not prevent pregnancy, but may contribute to vaginal infections.
* Although some sex positions may encourage pregnancy, no sexual positions prevent pregnancy. Having sex while standing up or with a woman on top will not keep the sperm from entering the uterus. The force of ejaculation, the contractions of the uterus caused by prostaglandins[ citation needed ] in the semen, as well as ability of sperm to swim overrides gravity.
* Urinating after sex does not prevent pregnancy and is not a form of birth control, although it is often advised anyway to help prevent urinary tract infections.[26]
* Toothpaste cannot be used as an effective contraceptive[27].

Effectiveness

Effectiveness is measured by how many women become pregnant using a particular birth control method in the first year of use. Thus, if 100 women use a method that has a 12 percent first-year failure rate, then sometime during the first year of use, 12 of the women should become pregnant.

The most effective methods in typical use are those that do not depend upon regular user action. Surgical sterilization, Depo-Provera, implants, and intrauterine devices (IUDs) all have first-year failure rates of less than one percent for perfect use. Sterilization, implants, and IUDs also have typical failure rates under one percent. The typical failure rate of Depo-Provera is disagreed upon, with figures ranging from less than one percent up to three percent.[28][29]

Other methods may be highly effective if used consistently and correctly, but can have typical use first-year failure rates that are considerably higher due to incorrect or ineffective usage by the user. Hormonal contraceptive pills, patches or rings, fertility awareness methods, and the lactational amenorrhea method (LAM), if used strictly, have first-year (or for LAM, first-6-month) failure rates of less than 1%.[30][31][32][33] In one survey, typical use first-year failure rates of hormonal contraceptive pills (and by extrapolation, patches or rings) were as high as five percent per year. Fertility awareness methods as a whole have typical use first-year failure rates as high as 25 percent per year; however, as stated above, perfect use of these methods reduces the first-year failure rate to less than 1%.[28]

Condoms and cervical barriers such as the diaphragm have similar typical use first-year failure rates (14 and 20 percent, respectively), but perfect usage of the condom is more effective (three percent first-year failure vs six percent) and condoms have the additional feature of helping to prevent the spread of sexually transmitted diseases such as the HIV virus. The withdrawal method, if used consistently and correctly, has a first-year failure rate of four percent. Due to the difficulty of consistently using withdrawal correctly, it has a typical use first-year failure rate of 19 percent,[28] and is not recommended by some medical professionals.[34]

Protection against sexually transmitted infections

Not all methods of birth control offer protection against sexually transmitted infections. Abstinence from all forms of sexual behavior will protect against the sexual transmission of these infections. The male latex condom offers some protection against some of these diseases with correct and consistent use, as does the female condom, although the latter has only been approved for vaginal sex. The female condom may offer greater protection against sexually transmitted infections that pass through skin to skin contact, as the outer ring covers more exposed skin than the male condom, and can be used during anal sex to guard against sexually transmitted infections. However, the female condom can be difficult to use. Frequently a woman can improperly insert it, even if she believes she is using it correctly.[ citation needed ]

The remaining methods of birth control do not offer significant protection against the sexual transmission of these diseases.

However, so-called sexually transmitted infections may also be transmitted non-sexually, and therefore, abstinence from sexual behavior does not guarantee 100 percent protection against sexually transmitted infections. For example, HIV may be transmitted through contaminated needles which may be used in intravenous drug use, tattooing, body piercing, or injections. Health-care workers have acquired HIV through occupational exposure to accidental injuries with needles.[35]

Religious and cultural attitudes

Religious views on birth control


Religions vary widely in their views of the ethics of birth control. In Christianity, the Roman Catholic Church accepts only Natural Family Planning,[36] while Protestants maintain a wide range of views from allowing none to very lenient.[37] Views in Judaism range from the stricter Orthodox sect to the more relaxed Reform sect.[38] In Islam, contraceptives are allowed if they do not threaten health or lead to sterility, although their use is discouraged.[39] Hindus may use both natural and artificial contraceptives.[40] A common Buddhist view of birth control is that preventing conception is ethically acceptable, while intervening after conception has occurred or may have occurred is not.[41]

Birth control education

Many teenagers, most commonly in developed countries, receive some form of sex education in school. What information should be provided in such programs is hotly contested, especially in the United States and Great Britain. Possible topics include reproductive anatomy, human sexual behavior, information on sexually transmitted diseases (STDs), social aspects of sexual interaction, negotiating skills intended to help teens follow through with a decision to remain abstinent or to use birth control during sex, and information on birth control methods.

One type of sex education program used mainly in the United States is called abstinence-only education, and it promotes sexual abstinence until marriage. The programs do not encourage birth control, often provide inaccurate information about contraceptives and sexuality[42], stress failure rates of condoms and other contraceptives, and teach strategies for avoiding sexually intimate situations. Advocates of abstinence-only education believe that the programs will result in decreased rates of teenage pregnancy and STD infection. In a non-random, Internet survey of 1,400 women who found and completed a 10-minute multiple-choice online questionnaire listed in one of several popular search engines, women who received sex education from schools providing primarily abstinence information, or contraception and abstinence information equally, reported fewer unplanned pregnancies than those who received primarily contraceptive information, who in turn reported fewer unplanned pregnancies than those who received no information.[43] However, randomized controlled trials demonstrate that abstinence-only sex education programs increase the rates of pregnancy and STDs in the teenage population.[44][45] Professional medical organizations, including the AMA, AAP, ACOG, APHA, and Society for Adolescent Medicine, support comprehensive sex education (providing abstinence and contraceptive information) and oppose the sole use of abstinence-only sex education.[46][47]

Demographic analysis

Demographic analysis includes the sets of methods that allow us to measure the dimensions and dynamics of populations. These methods have primarily been developed to study human populations, but are extended to a variety of areas where researchers want to know how populations of social actors can change across time through processes of birth, death, and migration. In the context of human biological populations demographic analysis uses administrative records to develop an independent estimate of the population [1]. Demographic analysis estimates are often considered a reliable standard for judging the accuracy of the census information gathered at any time. In the labor force demographic analysis is used to estimate sizes and flows of populations of workers; in population ecology the focus is on the birth, death and movement of firms and institutional forms.

Introduction

Demography is the statistical and mathematical study of the size, composition, and spatial distribution of human populations and how these features change over time. Data is obtained from a census of the population and from registries-records of events like birth, deaths, migrations, marriages, divorces, diseases, and employment. To do this, there needs to be an understanding of how they are calculated and the questions they answers which is included in these four concepts: population change, standardization of population numbers, the demographic bookkeeping equation, and population composition.

Population Change

Population change is analyzed by measuring the change between one population size to another. Global population continues to rise, which makes population change an essential component to demographics. This is calculated by taking one population size minus the population size in an earlier census. The best way of measuring population change is using the intercensal percentage change. The intercensal percentage change is the absolute change in population between the censuses divided by the population size in the earlier census. Next, multiply this by 100 to receive a percentage. When this statistic is achieved, the population growth between two or more nations that differ in size, can be accurately measured and examined.

Standardization (of population numbers)

For there to be a significant comparison, numbers must be altered for the size of the population that is under study. For example, the fertility rate is calculated as the ratio of the number of births to women of childbearing are to the total number of women in this age range (multiplied by 1000). If these adjustments were not made, we would not know if a nation with a higher rate of births or deaths has a population with more women of childbearing age or more births per eligible woman.

Within the category of standardization, there are two major approaches: direct standardization and indirect standardization.

Direct Standardization

Direct standardization is able to be used when the population being studied is large enough for age-specific rate are stable.

Indirect Standardization

Indirect standardization is used when a population is small enough that the number of events (births, deaths, etc.) are also small. In this case, methods must be used to produce a standardized mortality rate (SMR) or standardized incidence rate (SIR)

For examples of standardization see the following [7]

Demographic Bookkeeping (or balancing) equation

Demographic bookkeeping is used in the identification of four main components of population growth during any given time interval.

The demographic bookkeeping equation is as follows:

P2 = P1 + (B - D) + (Mi - Mo)

The four components being studied by this equation are Population Growth (P1, P2), Births (B), Deaths (D), and In (Mi) and Out (Mo) Migration.

Meaning, the population at any time is equal to the earlier population plus the excess of births over deaths in the time, plus the amount of in-migration minus the amount of out-migration.

Population Composition

Population composition is the description of population defined by characteristics such as age, race, sex or marital status. These descriptions can be necessary for understanding the social dynamics from historical and comparative research. This data is often compared using a population pyramid.

Population composition is also a very important part of historical research. Information ranging back hundreds of years is not always worthwhile, because the numbers of people for which data are available may not provide the information that is important (such as population size). Lack of information on the original data-collection procedures may prevent accurate evaluation of data quality.

Demographic Analysis in Institutions and Organizations

Labor markets

The deomographic anaylysis of labor markets can be used to show slow population growth, population aging, and the increased importance of immigration. The U.S. Census Bureau will project that in the next 100 years, the United States will face some dramatic demographic changes. The population is expected to grow more slowly and age more rapidly than ever before and the nation will become a nation of immigrants. This influx is projected to rise over the next century as new immigrants and their children will account for over half the U.S. population. These demographic shifts could ignite major adjustments in the economy, more specifically, in labor markets.

Turnover and in internal labor markets

People decide to exit organizations for many reasons, such as, better jobs, dissatisfaction, and concerns within the family. The causes of turnover can be slpit into two separate factors, one linked with the culture of the organization, and the other relating to all other factors. People who do not fully accept a culture might leave voluntarily. Or, some individuals might leave because they fail to fit in and fail to change within a particular organization.

Population ecology

A basic definition of population ecology is a study of the distribution and abundance of organisms. As it relates to organizations and demography, organizations go through various liabilities to their continued survival. Hospitals, like all other large and complex organizations are impacted in the environment they work. For example, a study was done on the closure of acute care hospitals in Florida between a particular time. The study examined effect size, age, and niche density of these particular hospitals. A population theory says that organizational outcomes are mostly determined by environmental factors. Among several factors of the theory, there are four that apply to the hospital closure example: size, age, density of niches in which organizations operate, and density of niches in which organizations are estbalished.


Business Organizations

Problems in which demographers may be called upon to assist business organizations are when determining the best prospective location in an area of a branch store or service outlet, predicting the demand for a new product, and to analyze certain dynamics of a company's workforce. Choosing a new location for a branch of a bank, choosing the area in which to start a new supermarket, consulting a bank loan officer that a particular location would be a beneficial site to start a car wash, and determining what shopping area would be best to buy and be redeveloped in metropolis area are types of problems in which demographers can be called upon. Standardization is a useful demographic technique used in the analysis of a business. It can be used as an interpretive and analytic tool for the comparison of different markets.


Nonprofit Organizations

These organizations have interests about the number and characteristics of their clients so they can maximize the sale of their products, their outlook on their influence, or the ends of their power, services, and beneficial works.

Further reading

* Ehrlich, Paul R. (1968), The Population Bomb Controversial Neo-Malthusianist Pamphlet
* Longman Phillip (2004), The Empty Cradle: How Falling Birth Rates Threaten Global Prosperity and What to do About it.
* Korotayev Andrey & Daria Khaltourina (2006). Introduction to Social Macrodynamics: Compact Macromodels of the World System Growth. Moscow: URSS ISBN 5-484-00414-4 [8]
* McFalls,Joe (2007), Population: A Lively Introduction, Population Reference Bureau [9]
* Perry, Marc J. & Mackun, Paul J. Population Change & Distribution: Census 2000 Brief. (2001)
* Preston, Samuel; Heuveline,Patrick; and Guillot Michel. 2000. Demography: Measuring and Modeling Population Processes. Blackwell Publishing.
* Schutt, Russell K. 2006. "Investigating the Social World: The Process and Practice of Research". SAGE Publications.
* Siegal, Jacob S. (2002), Applied Demography: Applications to Business, Government, Law, and Public Policy. San Diego: Academic Press.
* Wattenberg,Ben J. (2004), How the New Demography of Depopulation Will Shape Our Future. Chicago: R. Dee, ISBN 1-56663-606-X

Demography

Demography is the statistical study of all populations. It can be a very general science that can be applied to any kind of dynamic population, that is, one that changes over time or space (see population dynamics). It encompasses the study of the size, structure and distribution of populations, and spatial and/or temporal changes in them in response to birth, death, migration and aging.

Human demography is the most well known discipline of demography, and typically what people refer to when using the term demography. Demographic analysis can be applied to whole societies or to groups defined by criteria such as education, nationality, religion and ethnicity. In academia, demography is often regarded as a branch of either anthropology, economics, or sociology. Formal demography limits its object of study to the measurement of populations processes, while the more broad field of social demography population studies also analyze the relationships between economic, social, cultural and biological processes influencing a population.[1]

The term demographics is often used erroneously for demography, but refers rather to selected population characteristics as used in government, marketing or opinion research, or the demographic profiles used in such research.

Data and methods

There are two methods of data collection: direct and indirect. Direct data come from vital statistics registries that track all births and deaths as well as certain changes in legal status such as marriage, divorce, and migration (registration of place of residence). In developed countries with good registration systems (such as the United States and much of Europe), registry statistics are the best method for estimating the number of births and deaths.

The census is the other common direct method of collecting demographic data. A census is usually conducted by a national government and attempts to enumerate every person in a country. However, in contrast to vital statistics data, which are typically collected continuously and summarized on an annual basis, censuses typically occur only every 10 years or so, and thus are not usually the best source of data on births and deaths. Analyses are conducted after a census to estimate how much over or undercounting took place. Censuses do more than just count people. They typically collect information about families or households, as well as about such individual characteristics as age, sex, marital status, literacy/education, employment status and occupation, and geographical location. They may also collect data on migration (or place of birth or of previous residence), language, religion, nationality (or ethnicity or race), and citizenship. In countries in which the vital registration system may be incomplete, the censuses are also used as a direct source of information about fertility and mortality; for example the censuses of the People's Republic of China gather information on births and deaths that occurred in the 18 months immediately preceding the census.

Indirect methods of data collections are required in countries where full data are not available, such as is the case in much of the developing world. One of these techniques is the sister method, where survey researchers ask women how many of their sisters have died or had children and at what age. With these surveys, researchers can then indirectly estimate birth or death rates for the entire population. Other indirect methods include asking people about siblings, parents, and children.

There are a variety of demographic methods for modeling population processes. They include models of mortality (including the life table, Gompertz models, hazards models, Cox proportional hazards models, multiple decrement life tables, Brass relational logits), fertility (Hernes model, Coale-Trussell models, parity progression ratios), marriage (Singulate Mean at Marriage, Page model), disability (Sullivan's method, multistate life tables), population projections (Lee Carter, the Leslie Matrix), and population momentum (Keyfitz).

Important concepts

Important concepts in demography include:

* The crude birth rate, the annual number of live births per 1000 people.
* The general fertility rate, the annual number of live births per 1000 women of childbearing age (often taken to be from 15 to 49 years old, but sometimes from 15 to 44).
* age-specific fertility rates, the annual number of live births per 1000 women in particular age groups (usually age 15-19, 20-24 etc.)
* The crude death rate, the annual number of deaths per 1000 people.
* The infant mortality rate, the annual number of deaths of children less than 1 year old per 1000 live births.
* The expectation of life (or life expectancy), the number of years which an individual at a given age could expect to live at present mortality levels.
* The total fertility rate, the number of live births per woman completing her reproductive life, if her childbearing at each age reflected current age-specific fertility rates.
* The gross reproduction rate, the number of daughters who would be born to a woman completing her reproductive life at current age-specific fertility rates.
* The net reproduction ratio is the expected number of daughters, per newborn prospective mother, who may or may not survive to and through the ages of childbearing.

Note that the crude death rate as defined above and applied to a whole population can give a misleading impression. For example, the number of deaths per 1000 people can be higher for developed nations than in less-developed countries, despite standards of health being better in developed countries. This is because developed countries have relatively more older people, who are more likely to die in a given year, so that the overall mortality rate can be higher even if the mortality rate at any given age is lower. A more complete picture of mortality is given by a life table which summarises mortality separately at each age. A life table is necessary to give a good estimate of life expectancy.

The fertility rates can also give a misleading impression that a population is growing faster than it in fact is, because measurement of fertility rates only involves the reproductive rate of women, and does not adjust for the sex ratio. For example, if a population has a total fertility rate of 4.0 but the sex ratio is 66/34 (twice as many men as women), this population is actually growing at a slower natural increase rate than would a population having a fertility rate of 3.0 and a sex ratio of 50/50. This distortion is greatest in India and Myanmar, and is present in China as well.

Basic demographic equation

Suppose that a country (or other entity) contains Populationt persons at time t. What is the size of the population at time t + 1 ?

Populationt + 1 = Populationt + Naturalincreaset + Netmigrationt

Natural increase from time t to t + 1:

Naturalincreaset = Birthst − Deathst

Net migration from time t to t + 1:

Netmigrationt = Immigrationt − Emigrationt

This basic equation can also be applied to subpopulations. For example, the population size of ethnic groups or nationalities within a given society or country is subject to the same sources of change. However, when dealing with ethnic groups, "net migration" might have to be subdivided into physical migration and ethnic reidentification (assimilation). Individuals who change their ethnic self-labels or whose ethnic classification in government statistics changes over time may be thought of as migrating or moving from one population subcategory to another.[2]

More generally, while the basic demographic equation holds true by definition, in practice the recording and counting of events (births, deaths, immigration, emigration) and the enumeration of the total population size are subject to error. So allowance needs to be made for error in the underlying statistics when any accounting of population size or change is made.

History

Ibn Khaldun (1332-1406) is regarded as the "father of demography" for his economic analysis of social organization which produced the first scientific and theoretical work on population, development, and group dynamics. His Muqaddimah also laid the groundwork for his observation of the role of state, communication and propaganda in history.[3]

The Natural and Political Observations ... upon the Bills of Mortality (1662) of John Graunt contains a primitive form of life table. Mathematicians, such as Edmond Halley, developed the life table as the basis for life insurance mathematics. Richard Price was credited with the first textbook on life contingencies published in 1771,[4] followed later by Augustus de Morgan, ‘On the Application of Probabilities to Life Contingencies’, (1838).[5]

At the end of the 18th century, Thomas Malthus concluded that, if unchecked, populations would be subject to exponential growth. He feared that population growth would tend to outstrip growth in food production, leading to ever increasing famine and poverty (see Malthusian catastrophe); he is seen as the intellectual father of ideas of overpopulation and the limits to growth. Later more sophisticated and realistic models were presented by e.g. Benjamin Gompertz and Verhulst.

The period 1860-1910 can be characterized as a period of transition wherein demography emerged from statistics as a separate field of interest. This period included a panoply of international ‘great demographers’ like Adolphe Quételet (1796-1874), William Farr (1807-1883), Louis-Adolphe Bertillon (1821-1883) and his son Jacques (1851-1922), Joseph Körösi (1844-1906), Anders Nicolas Kaier (1838-1919), Richard Böckh (1824-1907), Wilhelm Lexis (1837-1914) and Luigi Bodio (1840-1920) contributed to the development of demography and to the toolkit of methods and techniques of demographic analysis. [6]

The demographic transition
World population from 500CE to 2150, based on UN 2004 projections (red, orange, green) and US Census Bureau historical estimates (black). Only the section in blue is from reliable counts, not estimates or projections.
World population from 500CE to 2150, based on UN 2004 projections (red, orange, green) and US Census Bureau historical estimates (black). Only the section in blue is from reliable counts, not estimates or projections.

Contrary to Malthus' predictions and in line with his thoughts on moral restraint, natural population growth in most developed countries has diminished to close to zero, without being held in check by famine or lack of resources, as people in developed nations have shown a tendency to have fewer children. The fall in population growth has occurred despite large rises in life expectancy in these countries. This pattern of population growth, with slow (or no) growth in pre-industrial societies, followed by fast growth as the society develops and industrialises, followed by slow growth again as it becomes more affluent, is known as the demographic transition.

Similar trends are now becoming visible in ever more developing countries, so that far from spiralling out of control, world population growth is expected to slow markedly in the next century, coming to an eventual standstill or even declining. The change is likely to be accompanied by major shifts in the proportion of world population in particular regions. The United Nations Population Division expects the absolute number of infants and toddlers in the world to begin to fall by 2015, and the number of children under 15 by 2025. The figure in this section shows the latest (2004) UN projections of world population out to the year 2150 (red = high, orange = medium, green = low). The UN "medium" projection shows world population reaching an approximate equilibrium at 9 billion by 2075. Working independently, demographers at the International Institute for Applied Systems Analysis in Austria expect world population to peak at 9 billion by 2070. Throughout the 21st century, the average age of the population is likely to continue to rise.

The science of population

Populations change through three processes: fertility, mortality, and migration. Fertility involves the number of children that women have and is to be contrasted with fecundity (a woman's childbearing potential).[7] Mortality is the study of the causes, consequences, and measurement of processes affecting death to members of the population. Demographers most commonly study mortality using the Life Table, a statistical device which provides information about the mortality conditions (most notably the life expectancy) in the population.[8] Migration refers to the movement of persons from an origin place to a destination place across some pre-defined, political boundary. Migration researchers do not designate movements 'migrations' unless they are somewhat permanent. Thus demographers do not consider tourists and travelers to be migrating. While demographers who study migration typically do so through census data on place of residence, indirect sources of data including tax forms and labor force surveys are also important.[9]

Demography is today widely taught in many universities across the world, attracting students with initial training in social sciences, statistics or health studies. Being at the crossroads of several disciplines such as geography, economics, sociology or epidemiology, demography offers tools to approach a large range of population issues by combining a more technical quantitative approach that represents the core of the discipline with many other methods borrowed from social or other sciences. Demographic research is conducted in universities, in research institutes as well as in statistical departments and in several international agencies. Population institutions are part of the Cicred (International Committee for Coordination of Demographic Research) network while most individual scientists engaged in demographic research are members of the International Union for the Scientific Study of Population – IUSSP or, in the United States, in the Population Association of America.

Notes

1. ^ Andrew Hinde Demographic Methods Ch. 1 ISBN 0-340-71892-7
2. ^ See, for example, Barbara A. Anderson and Brian D. Silver, "Estimating Russification of Ethnic Identity Among Non-Russians in the USSR," Demography, Vol. 20, No. 4 (Nov., 1983): 461-489.
3. ^ H. Mowlana (2001). "Information in the Arab World", Cooperation South Journal 1.
4. ^ “Our Yesterdays: the History of the Actuarial Profession in North America, 1809-1979,” by E.J. (Jack) Moorhead, FSA, ( 1/23/10 – 2/21/04), published by the Society of Actuaries as part of the profession’s centennial celebration in 1989.
5. ^ The History of Insurance, Vol 3, Edited by David Jenkins and Takau Yoneyama (1 85196 527 0): 8 Volume Set: ( 2000) Availability: Japan: Kinokuniya)
6. ^ de Gans, Henk and Frans van Poppel (2000) Contributions from the margins. Dutch statisticians, actuaries and medical doctors and the methods of demography in the time of Wilhelm Lexis. Workshop on ‘Lexis in Context: German and Eastern& Northern European Contributions to Demography 1860-1910’ at the Max Planck Institute for Demographic Research, Rostock , August 28 and 29, 2000.
7. ^ John Bongaarts. The Fertility-Inhibiting Effects of the Intermediate Fertility Variables. Studies in Family Planning, Vol. 13, No. 6/7. (Jun. - Jul., 1982), pp. 179-189.
8. ^ N C H S - Life Tables
9. ^ Donald T. Rowland Demographic Methods and Concepts Ch. 11 ISBN 0-19-875263-6