A fertility rate measures how many children women in a given population are having. The most widely used version, the total fertility rate (TFR), estimates the average number of children a woman would have over her lifetime based on current birth patterns. Globally, the TFR in 2024 was 2.2 births per woman, down from around 5 in the 1960s.
How Fertility Rate Is Measured
Demographers use two main metrics. The general fertility rate counts the number of live births per 1,000 women of childbearing age (15 to 44) in a given year. It’s a straightforward snapshot of how many babies are being born relative to the number of women who could be having them.
The total fertility rate is more useful for comparing countries and tracking trends over time. It works by looking at birth rates for women in each five-year age group (15 to 19, 20 to 24, and so on up to 45 to 49), then adding those rates together. The result estimates how many children 1,000 women would have if they all lived through their childbearing years under today’s birth patterns. A TFR of 1,800, for instance, translates to 1.8 births per woman. The key advantage of TFR is that it adjusts for the age makeup of a population, so you can fairly compare a country with a young population to one with an older one.
What “Replacement Level” Means
You’ll often hear 2.1 cited as the “replacement level” fertility rate. This is the number of births per woman needed for a population to maintain its size without immigration. It’s slightly above 2.0 because not every child survives to adulthood, and slightly more boys are born than girls. In countries with higher child mortality, replacement level can be significantly higher than 2.1.
When a country’s TFR stays below replacement for an extended period, its population eventually shrinks and skews older. When it stays above replacement, the population grows and stays younger.
Where Fertility Rates Stand Today
The global TFR has been falling for decades. It dropped from roughly 5 births per woman in the 1950s and 1960s to 3.3 in 1990 and 2.2 in 2024, according to the United Nations. That 2024 figure is just barely above replacement level, and it came in lower than what the UN had projected a decade earlier (2.4), meaning the decline has been faster than expected.
The United States sits well below replacement. The provisional TFR for 2024 was about 1.63 births per woman, a slight uptick of less than 1% from 2023. The U.S. rate declined by roughly 2% per year between 2014 and 2020 and has fluctuated since then without recovering to earlier levels.
Fertility rates vary enormously by region. Many countries in sub-Saharan Africa still have TFRs above 4 or 5, while much of East Asia and Southern Europe has rates below 1.3. South Korea, for example, has reported some of the lowest fertility rates ever recorded in a nation.
Why Fertility Rates Are Falling
No single factor drives the decline. Instead, a cluster of economic and social forces push in the same direction.
- Education and careers: Higher education levels and professional careers lead women to delay childbearing. In many countries, women who pursue advanced degrees start families a decade later than previous generations did, reducing the total number of children they have.
- Cost of raising children: Housing costs, childcare expenses, and education fees make larger families financially difficult. In wealthier countries, children are an economic cost rather than an economic asset, reversing the incentive structure that once favored big families.
- Access to contraception: Widely available birth control gives women and couples the ability to choose when and whether to have children.
- Urbanization: Urban living is associated with smaller families. City life brings higher costs, smaller living spaces, and lifestyle patterns that favor fewer children.
- Delayed parenthood and biological limits: When couples wait until their 30s or 40s, natural fertility declines, and some who want children find it harder to conceive.
These forces compound each other. Immigrant populations, for instance, tend to have higher fertility rates than native-born populations, but their children’s fertility drops sharply in the second generation as education and income rise.
The Shift in When Women Have Children
In the United States, the age pattern of childbearing has changed dramatically. Between 1990 and 2023, the birth rate for women aged 20 to 24 fell by 51%. Meanwhile, rates for older women climbed: up 17% for ages 30 to 34, 71% for ages 35 to 39, and 127% for ages 40 to 44. Women aged 30 to 34 now have the highest birth rate of any age group in the U.S., a reversal from 1990 when that distinction belonged to women in their late 20s.
This shift isn’t just about preference. It reflects the reality that more women spend their 20s in education or building careers. The tradeoff is that delayed childbearing reduces overall fertility, because biological fertility declines with age and shorter remaining reproductive windows mean fewer total births.
Economic Consequences of Low Fertility
When fertility stays low for years, the population ages. Fewer young workers enter the labor force while the number of retirees grows. This creates pressure on government budgets in two directions: less tax revenue coming in and more spending going out on pensions and healthcare for older adults.
Analysis of 40 countries shows that fertility well above replacement would typically be most beneficial for government budgets. Countries with very low fertility face a particularly difficult math problem. Japan, with a TFR that averaged 1.34 between 2005 and 2010, already carries high public debt, making higher taxes and reduced benefits nearly inevitable. A population declining at 2% per year (roughly equivalent to a TFR of 1.1) would reduce per capita consumption by about 4% compared to a stable population.
There is a partial offset. Countries with fewer children tend to invest more in each child’s education, producing a more productive workforce. This human capital investment can compensate for having fewer workers, though it has limits. Gradual population decline can actually favor material living standards in some ways, since there’s less need to build new infrastructure for each generation. The problems become severe only when the decline is steep or rapid.
What Governments Have Tried
Many countries have introduced pro-natalist policies to boost birth rates, with mixed results. Cash incentives at birth have been the most common approach. Australia introduced a one-time birth payment in 2004 and saw fertility rise 12.8%. Spain offered €2,500 per birth from 2007 to 2010 and saw a 4.7% increase. Hungary’s cash benefits for second, third, and fourth children increased fertility by 26%, 32%, and 14% respectively.
Parental leave policies also show measurable effects. Germany’s parental leave reform increased fertility by close to 23% among highly educated working women. In Iceland, cuts to parental leave led to a 15.8% decline in births among women aged 25 to 34, while increases in leave raised estimated births by 9.3%.
Childcare subsidies and coverage tend to have the strongest effect on educated women, who are otherwise most likely to limit family size due to career concerns. Countries like Australia, France, Hungary, Greece, and the UK spend over 1.3% of GDP on family cash benefits, while Japan and South Korea spend less than 1%, a gap that may partially explain the extremely low fertility in East Asia.
The overall pattern is that financial support can nudge fertility rates upward, but no country has used policy alone to fully reverse a sustained decline. Most interventions produce modest, single-digit percentage gains. The deepest drivers of low fertility, including the cost structure of modern life, women’s educational and career opportunities, and shifting cultural expectations around family size, are not easily changed by government checks.