Total fertility rate
The total fertility rate of a population is the average number of children that are born to a woman over her lifetime, if they were to experience the exact current age-specific fertility rates through their lifetime, and they were to live from birth until the end of their reproductive life.
As of 2023, the total fertility rate varied widely across the world, from 0.7 in South Korea, to 6.1 in Niger. Among sovereign countries that were not city states or microstates, in 2025 the following countries had a TFR of 1.0 or lower: China, South Korea, Taiwan, Thailand, and Ukraine; the following countries had a TFR of 1.2 or lower: Argentina, Belarus, Chile, Colombia, Costa Rica, Estonia, Italy, Japan, Lithuania, Poland, Spain, and Uruguay.
Fertility tends to be inversely correlated with levels of economic development. Historically, developed countries have significantly lower fertility rates, generally correlated with greater wealth, education, urbanization, and other factors. Conversely, in least developed countries, fertility rates tend to be higher. Families desire children for their labor 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, and lower rates of female employment.
From antiquity to the beginning of the industrial revolution, around the year 1800, total fertility rates of 4.5 to 7.5 were common around the world. After this TFR declined only slightly and up until the 1960s the global average TFR was still 5. Since then, global average TFR has dropped steadily to less than half that number, 2.3 births per woman in 2023.
The United Nations predicts that global fertility will continue to decline for the remainder of this century and reach a below-replacement level of 1.8 by 2100, and that world population will peak in 2084.
How TFR is actually computed
The TFR for year 2024 is usually computed by this formula:Ideally and more correctly, it should instead be computed by this formula:
But this second formula requires fertility rates for each single-year age group. And so, government and international agencies usually prefer the first formula.
Related metrics
Net reproduction rate
An alternative measure of fertility is the net reproduction rate, which calculates the number of daughters a female would have in her lifetime if she were subject to prevailing age-specific fertility and mortality rates in a given year. When the NRR is exactly 1, each generation of females is precisely replacing itself.The NRR is not as commonly used as the TFR, but it is particularly relevant in cases where the number of male babies born is very high due to gender imbalance and sex selection. This is a significant consideration in world population dynamics, especially given the high level of gender imbalance in the heavily populated nations of China and India. The gross reproduction rate is the same as the NRR, except that, like the TFR, it disregards life expectancy.
Total period fertility rate
The TFR, sometimes called TPFR—total period fertility rate, is a better index of fertility than the crude birth rate 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. TFR and long term population growth rate, g, are closely related. For a population structure in a steady state, growth rate equals, where is the mean age for childbearing women.
Tempo effect
The TPFR is affected by a tempo effect—if age of childbearing increases, and life cycle fertility is 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 women give birth to enough babies to sustain population levels, assuming that mortality rates remain constant and net migration is zero. If replacement level fertility is sustained over a sufficiently long period, each generation will exactly replace itself. In 2003, the replacement fertility rate was 2.1 births per female for most developed countries, but could be as high as 3.5 in undeveloped countries because of higher mortality rates, especially child mortality. The global average for the replacement total fertility rate, eventually leading to a stable global population, for 2010–2015, was 2.3 children per female.Lowest-low fertility
The term lowest-low fertility is defined as a TFR at or below 1.3. Lowest-low fertility is found almost mostly within East Asian countries and European countries. The East Asian American community in the United States also exhibits lowest-low fertility. At one point in the late 20th century and early 21st century this was also observed in Eastern and Southern Europe. However, the fertility rate then began to rise in most countries of Europe. Since the 2020s, however, TFR are falling again: in 2023, Spain's TFR fell to 1.19, and Italy's TFR fell to 1.2 children per woman. In Canada, the TFR in 2023 fell to its lowest ever recorded level, at 1.26 children per woman, with Statistics Canada reporting that Canada "has now joined the group of 'lowest-low' fertility countries".The lowest TFR recorded anywhere in the world in recorded history, is for the Xiangyang district of Jiamusi city which had a TFR of 0.41 in 2000. In 2023, South Korea's TFR was 0.72 the world's lowest for that year.
Outside Asia, the lowest TFR ever recorded was 0.80 for Eastern Germany in 1994. The low Eastern German value was influenced by a change to higher maternal age at birth, with the consequence that neither older cohorts, who often already had children, nor younger cohorts, who were postponing childbirth, had many children during that time. The total cohort fertility rate of each age cohort of women in East Germany did not drop as significantly.
Population-lag effect
A population that maintained a TFR of 3.8 over an extended period, without a correspondingly high death or emigration rate, would increase rapidly, doubling period ≈32 years. A population that maintained a TFR of 2.0 over a long time would decrease, unless it had a large enough immigration.It may take several generations for a change in the total fertility rate to be reflected in birth rate, 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 childbearing years.
This phenomenon carries forward for several generations and is called population momentum, population inertia, or population-lag effect. This time-lag effect is of great importance to the growth rates of human populations.
TFR and long-term population growth rate, g, are closely related. For a population structure in a steady state and with zero migration,, where is mean age for childbearing women and thus. At the left side is shown the empirical relation between the two variables in a cross-section of countries with the most recent y-y growth rate.
The parameter should be an estimate of the ; here equal to years, way off the mark because of population momentum. E.g. for, g should be exactly zero, which is seen not to be the case.
Influencing factors
Since the mid-20th-century baby boom that followed the end of World War II, declining fertility rates have been observed in many modern industrialized, affluent societies. Negative fertility factors are often cited as a response to overpopulation. Countries and geographic regions that are currently experiencing the highest rates of declining populations include Western Europe, Japan, the Russian Federation, and South Korea. Populations in other industrialized countries, such as the United Kingdom and the United States, and developing, poorer regions of the world, including the Balkans, Central Asia, the Middle East, and Sub-Saharan Africa, are also being impacted.Many of these fertility factors may differ by levels of social and economic inequality, wealth disparities, religiosity, and social class in each country. For instance, Nordic countries and France are among the least religious in Europe but have the highest TFR, while the opposite is true about Cyprus, Greece, Poland, Portugal, and Spain. The impact of human development on TFR can best be summarized by a quote from Karan Singh at the 1974 United Nations world population conference in Bucharest, where he declared that "development is the best contraceptive."
National efforts to increase or decrease fertility
Governments have often set population targets, to either increase or decrease the total fertility rate, or to have certain ethnic or socioeconomic groups have a lower or higher fertility rate. Often such policies have been interventionist, and abusive. The most notorious natalist policies of the 20th century include those in communist Romania and communist Albania, under Nicolae Ceaușescu and Enver Hoxha respectively.The natalist policy in Romania between 1967 and 1989 was very aggressive, including outlawing abortion and contraception, routine pregnancy tests for women, taxes on childlessness, and legal discrimination against childless people. It resulted in large numbers of children put into Romanian orphanages by parents who could not cope with raising them, street children in the 1990s, when many orphanages were closed and the children ended up on the streets, overcrowding in homes and schools, and over 9,000 women who died due to illegal abortions.
Conversely, in China the government sought to lower the fertility rate, and, as such, enacted the one-child policy, which included abuses such as forced abortions. In India, during the national emergency of 1975, a massive compulsory sterilization drive was carried out in India, but it is considered to be a failure and is criticized for being an abuse of power.
Some governments have sought to regulate which groups of society could reproduce through eugenic policies, including forced sterilizations of population groups they considered undesirable. Such policies were carried out against ethnic minorities in Europe and North America in the first half of the 20th century, and more recently in Latin America against the Indigenous population in the 1990s; in Peru, former President Alberto Fujimori has been accused of genocide and crimes against humanity as a result of a sterilization program put in place by his administration targeting indigenous people.
Within these historical contexts, the notion of reproductive rights has developed. Such rights are based on the concept that each person freely decides if, when, and how many children to have - not the state or religion. According to the Office of the United Nations High Commissioner for Human Rights, reproductive rights "rest on the recognition of the basic rights of all couples and individuals to decide freely and responsibly the number, spacing and timing of their children and to have the information and means to do so, and the right to attain the highest standard of sexual and reproductive health. It also includes the right to make decisions concerning reproduction free of discrimination, coercion and violence, as expressed in human rights documents".