Total Fertility Rate

# Total Fertility Rate

Overview
The total fertility rate (TFR, sometimes also called the fertility rate, period total fertility rate (PTFR) or total period fertility rate (TPFR)) of a population is the average number of children that would be born to a woman over her lifetime if (1) she were to experience the exact current age-specific fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...

rates (ASFRs) through her lifetime, and (2) she were to survive from birth through the end of her reproductive life. It is obtained by summing the single-year age-specific rates at a given time.
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Encyclopedia
The total fertility rate (TFR, sometimes also called the fertility rate, period total fertility rate (PTFR) or total period fertility rate (TPFR)) of a population is the average number of children that would be born to a woman over her lifetime if (1) she were to experience the exact current age-specific fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...

rates (ASFRs) through her lifetime, and (2) she were to survive from birth through the end of her reproductive life. It is obtained by summing the single-year age-specific rates at a given time.

## Parameter characteristics

World historical and predicted total fertility rates (1950–2100)
UN, medium variant, 2010 rev.
YearsTFRYearsTFRYearsTFR
1950–1955 4.95 2000–2005 2.62 2050–2055 1.61
1955–1960 4.89 2005–2010 2.52 2055–2060 1.54
1960–1965 4.91 2010–2015 2.34 2060–2065 1.47
1965–1970 4.85 2015–2020 2.19 2065–2070 1.38
1970–1975 4.45 2020–2025 2.10 2070–2075 1.32
1975–1980 3.84 2025–2030 2.02 2075–2080 1.26
1980–1985 3.59 2030–2035 1.95 2080–2085 1.25
1985–1990 3.39 2035–2040 1.82 2085–2090 1.24
1990–1995 3.04 2040–2045 1.74 2090–2095 1.24
1995–2000 2.79 2045–2050 1.67 2095–2100 1.23

The TFR is a synthetic rate, not based on the fertility of any real group of women since this would involve waiting until they had completed childbearing. Nor is it based on counting up the total number of children actually born over their lifetime. Instead, the TFR is based on the age-specific fertility rates of women in their "child-bearing years," which in conventional international statistical usage is ages 15–44 or 15-49.

The TFR is, therefore, a measure of the fertility of an imaginary woman who passes through her reproductive life subject to all the age-specific fertility rates for ages 15–49 that were recorded for a given population in a given year. The TFR represents the average number of children a woman would have were she to fast-forward through all her childbearing years in a single year, under all the age-specific fertility rates for that year. In other words, this rate is the number of children a woman would have if she was subject to prevailing fertility rates at all ages from a single given year, and survives throughout all her childbearing years.

### Net reproduction rate

An alternative fertility measure is the net reproduction rate
Net reproduction rate
The net reproduction rate is the average number of daughters that would be born to a female if she passed through her lifetime conforming to the age-specific fertility and mortality rates of a given year. This rate is similar to the gross reproduction rate but takes into account that some females...

(NRR), which measures the number of daughters a woman would have in her lifetime if she were subject to prevailing age-specific fertility and mortality rates in the given year. When the NRR is exactly one, then each generation of women is exactly reproducing itself. The NRR is less widely used than the TFR, and the United Nations stopped reporting NRR data for member nations after 1998. But the NRR is particularly relevant where the number of male babies born is very high – see gender imbalance and sex selection
Sex selection
Sex selection is the attempt to control the sex of the offspring to achieve a desired sex. It can be accomplished in several ways, both pre- and post-implantation of an embryo, as well as at birth...

. This is a significant factor in world population, due to the high level of gender imbalance in the very populous nations of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. The gross reproduction rate
Gross reproduction rate
The gross reproduction rate is the average number of daughters that would be born to a woman if she survived at least to the age of 45 and conformed to the age-specific fertility rate of a given year...

(GRR), is the same as the NRR, except that - like the TFR - it ignores life expectancy.

### Total period fertility rate

The TFR (or TPFR—total period fertility rate) is a better index of fertility than the Crude birth rate (annual number of births per thousand population) because it is independent of the age structure of the population, but it is a poorer estimate of actual completed family size than the total cohort fertility rate, which is obtained by summing the age-specific fertility rates that actually applied to each cohort as they aged through time. In particular, the TFR does not necessarily predict how many children young women now will eventually have, as their fertility rates in years to come may change from those of older women now. However, the TFR is a reasonable summary of current fertility levels.

#### Tempo effect

The TPFR (total period fertility rate) is affected by a tempo effect – if age of childbearing increases (and life cycle fertility in unchanged) then while the age of childbearing is increasing, TPFR will be lower (because the births are occurring later), and then the age of childbearing stops increasing, the TPFR will increase (due to the deferred births occurring in the later period) even though the life cycle fertility has been unchanged. In other words, the TPFR is a misleading measure of life cycle fertility when childbearing age is changing, due to this statistical artifact. This is a significant factor in some countries, such as the Czech republic and Spain in the 1990s. Some measures seek to adjust for this timing effect to gain a better measure of life cycle fertility.

### Replacement rates

Replacement fertility is the total fertility rate at which newborn girls would have an average of exactly one daughter over their lifetimes. That is, women have just enough female babies to replace themselves (or, equivalently, adults have just enough total babies to replace themselves).

If there were no mortality in the female population until the end of the childbearing years (generally taken as 44 or 49, though some exceptions exist) then the replacement level of TFR would be very close to 2.0 (actually slightly higher because of the excess of boy over girl births in human populations). However, the replacement level is also affected by mortality, especially childhood mortality. The replacement fertility
Sub-replacement fertility
Sub-replacement fertility is a total fertility rate that leads to each new generation being less populous than the previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4...

rate is roughly 2.1 births per woman for most industrialized countries (2.075 in the UK for example), but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement is 2.33 children per woman. At this rate, global population growth would trend towards zero.

## Population-lag effect

A population that maintained a TFR of 3.8 over an extended period of time without a correspondingly high death or emigration rate would increase rapidly, whereas a population that maintained a TFR of 2.0 over a long time would decline (unless it had a large enough immigration). However, it may take several generations for a change in the total fertility rate to be reflected in birth rate
Birth rate
Crude birth rate is the nativity or childbirths per 1,000 people per year . Another word used interchangeably with "birth rate" is "natality". When the crude birth rate is subtracted from the crude death rate, it reveals the rate of natural increase...

, because the age distribution must reach equilibrium. For example, a population that has recently dropped below replacement-level fertility will continue to grow, because the recent high fertility produced large numbers of young couples who would now be in their child-bearing years. This phenomenon carries forward for several generations and is called population momentum
Population momentum
Population momentum refers to population growth at the national level which would occur even if levels of childbearing immediately declined to replacement level. For countries with above-replacement fertility , population momentum represents natural increase to the population...

or population-lag effect. This time-lag effect is of great importance to the growth rates of human populations.

### Developed or developing countries

Developed countries usually have a much lower fertility rate due to greater wealth, education, and urbanization. Mortality rate
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

s are low, birth control
Birth control
Birth control is an umbrella term for several techniques and methods used to prevent fertilization or to interrupt pregnancy at various stages. Birth control techniques and methods include contraception , contragestion and abortion...

is understood and easily accessible, and costs are often deemed very high because of education, clothing, feeding, and social amenities. With wealth, contraception becomes affordable. However, in countries like Iran where contraception was made artificially affordable before the economy accelerated, birth rate also rapidly declined. Further, longer periods of time spent getting higher education often mean women have children later in life. The result is the demographic-economic paradox
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...

. Female labor participation rate also has substantial negative impact on fertility. However, this effect is neutralized among Nordic or liberalist countries.

In undeveloped countries on the other hand, families desire children for their labour and as caregivers for their parents in old age. Fertility rates are also higher due to the lack of access to contraceptives, generally lower levels of female education
Female education
Female education is a catch-all term for a complex of issues and debates surrounding education for females. It includes areas of gender equality and access to education, and its connection to the alleviation of poverty...

, and lower rates of female employment in industry.
 Period U.S. TotalFertilityRate 1930–34 2.1 1935–39 2.0 1940–44 2.5 1945–49 3.0 1950–54 3.3 1955–59 3.7 1960–64 3.4 1965–69 2.6 1970–74 2.1 1975–79 1.8

### United States

The total fertility rate in the United States after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

peaked at about 3.8 children per woman in the late 1950s and by 1999 was at 2 children. This means that an imaginary woman (defined in the introduction) who fast-forwarded through her life in the late 1950s would have been expected to have about four children, whereas an imaginary woman who fast-forwarded through her life in 1999 would have been expected to have only about two children in her lifetime. The fertility rate of the total U.S. population is at around the replacement level of about 2.1 children per woman. However, the fertility of the population of the United States is below replacement among those native born, and above replacement among immigrant families, most of whom come to the U.S. from countries with higher fertility than that of the U.S. However, the fertility rates of immigrants to the U.S. have been found to decrease sharply in the second generation, correlating with improved education and income.

According to a thesis submitted in 2005 to the Office of Graduate Studies of Texas A&M University
Texas A&M University
Texas A&M University is a coeducational public research university located in College Station, Texas . It is the flagship institution of the Texas A&M University System. The sixth-largest university in the United States, A&M's enrollment for Fall 2011 was over 50,000 for the first time in school...

, the lowest TFR recorded anywhere in the world in recorded history is for Xiangyang district of Jiamusi city (Heilongjiang, China) which had a TFR of 0.41. Outside China, the lowest TFR ever recorded was 0.80 for Eastern Germany in 1994.

### Europe

The average total fertility rate in Europe has been estimated to be 1.6 children per woman as of 2008.

## Factors

A systematic review
Systematic review
A systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...

of European fertility rates came to the result that European fertility rates do not seem to decrease significantly by availability of contraception
Contraception
Contraception is the prevention of the fusion of gametes during or after sexual activity. The term contraception is a contraction of contra, which means against, and the word conception, meaning fertilization...

. It pointed out significant factors for low fertility rates to include instability of modern partnerships and value changes. It also stated that government support of assisted reproductive technology
Assisted reproductive technology
Assisted reproductive technology is a general term referring to methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. Some forms of ART are also used in fertile couples for genetic reasons...

is beneficial for families, but its effect on total fertility rate is extremely small, and government policies that transfer cash to families for pregnancy and child support also only have small effects on total fertility rate.

The relationship between fertility and socio-economic development is a subject of debate in social sciences. The main issue of the debate is whether there exists a trade-off relationship between fertility and development. There is a demographic-economic paradox
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 the inverse correlation found between wealth and fertility within and between nations.

• Crude birth rate
• List of countries and territories by fertility rate
• List of people with the most children
• Demography
Demography
Demography is the statistical study of human population. It can be a very general science that can be applied to any kind of dynamic human population, that is, one that changes over time or space...

• Optimum population
Optimum population
The optimum population is the size of a population that is optimal. There are, however, various opinions on what "optimal" means in this usage, resulting in various end-targets for it, but estimations usually take ecological sustainability and carrying capacity more or less into account...

• Fertility-development controversy
Fertility-development controversy
The relationship between the total fertility rate and socio-economic development, which is measured by the human development index , is the subject of debate in social sciences....

Dynamics:
• Fertility and intelligence
Fertility and intelligence
Fertility and intelligence research investigates the relationship between fertility and intelligence. Demographic studies have indicated that in humans, fertility and intelligence tend to be inversely correlated, that is to say, the more intelligent, as measured by IQ tests, exhibit a lower total...

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...

• Sub-replacement fertility
Sub-replacement fertility
Sub-replacement fertility is a total fertility rate that leads to each new generation being less populous than the previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4...

• Zero population growth
Zero population growth
Zero population growth, sometimes abbreviated ZPG , is a condition of demographic balance where the number of people in a specified population neither grows nor declines, considered as a social aim....

Case studies:
• Aging of Europe
Aging of Europe
The Ageing of Europe, also known as the greying of Europe, is a demographic phenomenon in Europe characterized by a decrease in fertility, a decrease in mortality rate, and a higher life expectancy among Europeans.-Overall trends:...

• Aging of Japan
Aging of Japan
The ageing of Japan outweighs all other nations with the highest proportion of elderly citizens, 21% over the age of 65. In 1989, only 11.6% of the population was 65 years or older, but projections were that 25.6% would be in that age category by 2030...