The total fertility rate (TFR) 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 (ASFRs) 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, Greece, Japan, Lithuania, Malta, Poland, Spain, and Uruguay.
Several socioeconomic factors affect fertility, and presently approximately two thirds of the world's population lives in countries which have below replacement fertility rates.https://www.prb.org/resource/beyond-the-headlines-whats-really-happening-with-global-fertility/ Currently, the vast majority of countries which have above replacement fertility rates are situated in Africa, while the fertility rate is very low in much of East Asia.https://web.archive.org/web/20251229225430/https://www.cia.gov/the-world-factbook/field/total-fertility-rate/country-comparison/ 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. Since the 1960s, global decreases in total fertility rates may also reflect effects of pollution on reproduction.
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. Sub-Saharan Africa is the fastest growing world region, with 30% of all global births being in that region in 2021.https://www.economist.com/graphic-detail/2024/04/16/what-a-baby-boom-means-for-africa Among individual world countries, in 2024, births in India amounted for the highest global share, with 17.4% of all global births, followed by China, with 6% (see List of countries by number of births).
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 calculated The TFR typically refers to the total period fertility rate. The TFR for (say) year 2024 is usually calculated by this formula:
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Ideally and more correctly, it should instead be computed by this formula:
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But this second formula requires fertility rates for each single-year age group (which may not be available or may be poorly estimated). And so, government and international agencies usually prefer the first formula (which requires only fertility rates for each five-year age group).
The total period fertility rate is affected by the tempo effect caused by changes in average age of childbearing. If age of childbearing increases, and life cycle fertility is unchanged, then TPFR will be lower, because the births are occurring later. Tempo effect can be a significant factor in some countries, such as the Czech Republic and Spain in the 1990s.
Related metrics Net reproduction rate
An alternative measure of fertility is the net reproduction rate (NRR), 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. This is a significant consideration in world population dynamics in countries with a high level of gender imbalance and sex selection.
Total cohort fertility rate The total cohort fertility rate (TCFR) is the total number of children born to a women on average for an age cohort. The completed cohort fertility rate is a lagging indicator because it is measured at the end of the reproductive stage with the begin of menopause, typically around 45 years. Changes in cohort fertility can be decomposed into changes in childlessness rate and change in number of children per parent.
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 (2.1 in the UK, for example), 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 +List of sovereign states with lowest-low fertility as of 2025Country or regionTFRNumber of births0.70107,8120.80254,4570.835080.8730,0040.87416,5740.911660.937,920,0000.984,3381.01433,6781.0354,257 1.0317,4781.04384,0421.07238,2641.10168,7781.11321,1641.1245,3841.14146,1721.14355,4351.14671,2361.1528,9031.169,2401.1611,6371.2228,9001.2366,532 1.236,4391.25371,3731.2625,9351.2868,0511.2877,6361.2877,9021.3075,7181.3045,835
The term lowest-low fertility is defined as a TFR at or below 1.3. The term emerged in demographic research during the late 1990s and demographers Hans-Peter Kohler, Francesco C. Billari, and José Antonio Ortega popularized it in 2002, defining it as fertility below 1.3 children per woman.
Lowest-low fertility was first noted within East Asian and European countries but recently spread to the Americas; the lowest rates are still found in East Asia. The East Asian American community in the United States also exhibits lowest-low fertility. "The Behavior of U.S. minority CJK groups have another logical referent—the behavior of Chinese, Japanese and Korean national populations (shown in Fig. 1). What can we learn about low fertility in the origin countries from those that trace their origin there? Or in other words, what can the East Asian diaspora tell us about lowest-low fertility in East Asia? The most common explanation for fertility differences across developed countries (like those shown in Fig. 1) are institutional differences (see for instance, McDonald 2000a, b). However, it is striking that East Asians who have moved to a new location—to the U.S. with its dramatically different social institutions and one of the highest fertility rates in the developed world—have a fertility pattern that seems impervious to this dramatic contextual change. This simple observation challenges much contemporary thinking about policies to ameliorate low fertility and its negative consequences." At one point in the late 20th century and early 21st century this was concentrated in post-socialist Eastern Europe and parts of Southern Europe, affecting about 344 million people. 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".
In 2026, Stuart Gietel-Basten, a professor at the Hong Kong University of Science and Technology, and Ignacio Pardo, a professor at the University of the Republic in Uruguay, argue in Population and Development Review that the concept of lowest-low fertility needs to be reconsidered. They argue that, after the 2000s, countries with very low fertility began following increasingly divergent demographic trajectories, shaped not only by fertility but also by international migration, mortality, human capital, age structure, and other socioeconomic factors.
The lowest total fertility rate The lowest TFR recorded anywhere in the world in recorded history, is for the Xiangyang district of Jiamusi city (Heilongjiang, China) 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, before rebounding to 0.8 by 2025. In 2025, Taiwan overtook South Korea to record the lowest TFR for a country, at just 0.695 recorded.
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 (e.g. women born until the late 1960s), 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 (net) 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. 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.