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American women averaged more than seven children each until the early decades of the 19th century. After 1900, average fertility declined gradually, interrupted only by the baby boom following World War II. Another drop in the total fertility rate (TFR) came in the 1970s, due in large part to delayed marriage, widespread contraceptive use, and changes in abortion laws. The total fertility rate is the average number of children a woman would have in her lifetime based on the child­bearing rates of women in a population in a given year. In 2020, the U.S. TFR dropped to 1.64, the lowest level ever recorded.¹

What Contributes to Changing Fertility Patterns?

Historically, fertility in the United States has dropped temporarily during periods of economic decline, such as the Great Depression of the 1930s and the 1970s oil shocks. Such drops have typically lasted two to five years, affecting the timing of fertility but not the overall number of children that a woman would have in her lifetime.² But in the decade following the 2008 Great Recession, fertility rates continued to fall, with the exception of 2013 to 2014 when they increased slightly.

Between 2007 and 2020, the TFR in the United States declined from 2.12 to 1.64.³ This decline may signal a longer-term drop in lifetime fertility shaped by broader social factors, including postponement of marriage and childbearing to older ages and long-term increases in women’s educational attainment and labor force participation.⁴ Although most American women say they expect to have at least two children, many women delay childbearing whether by choice or circumstance to the point that they may end up having only one child or no children at all.⁵ Fifteen percent of U.S. women ages 40 to 44 in 2018 were childless.⁶

In 2011-2015, among American women ages 15 to 44, 20% had two children; 17% had one child; 18% had three or more children, and 45% had not had any children.⁷ What accounts for these differences? The most predictable and obvious fertility differential is age. For example, in 2011-2015, 83% of women ages 15 to 24 had not had any children, compared with only 15% of women ages 40 to 44. But education, race, religion, and many other social, economic, and cultural factors also influence childbearing.

While modern technology has expanded the age span in which women can have children, few women give birth before age 15 or after age 50. Birth rates by the age of the mother follow the same general pattern in most societies regardless of overall fertility levels: Rates are low for women in their teens, peak for women in their 20s or early 30s, and decline thereafter. But comparisons of the age-specific rates in different countries reveal significant variations (see Figure 1).

Figure 1: Age-Specific Birth Rates Vary Widely Across Countries, Births per 1,000 Women in Mali, South Korea, and the United States by Age of Mother

Sources: Institut National de la Statistique, Cellule de Planification et de Statistique Secteur Santé-Développement Social et Promotion de la Famille, and ICF, Mali Enquête Démographique et de Santé 2018: Rapport de synthèse (2019); CDC, National Center for Health Statistics, National Vital Statistics Reports; and United Nations (UN), Demographic Yearbook 2017 (New York: UN, 2017).

Similar trends occur in many of the world’s wealthy countries. In South Korea, the birth rate peaks among women in their early 30s. But in low-income countries with higher fertility rates such as Mali, where the TFR was an estimated 6.3 in 2018, rates typically peak among women in their early 20s and are higher for women of every age.⁸

During the 1960s and 1970s, postponement of childbearing resulted in a steep drop in the birth rate among American women ages 20 to 24. After 1975, U.S. birth rates rose for women in their 30s, as older mothers had the children they had postponed earlier in life. Today, U.S. birth rates are highest for women in the age groups of 25 to 29 and 30 to 34.⁹

Figure 2: U.S. Birth Rates Fall for Women in Their 20s, Rise for Women in Their 30s and 40s in Recent Decades, U.S. Birth Rates per 1,000 Women by Age of Mother, 1937–2018

Sources: Centers for Disease Control and Prevention, National Center for Health Statistics.

The birth rate for women ages 40 to 44 is lower in the United States today than it was during the baby boom years of the 1950s and early 1960s. However, the birth rate for women ages 40 to 44 has risen almost continuously since 1985 due to delays in childbearing at younger ages. The higher birth rates at older ages during the baby boom largely reflected women having third, fourth, or higher-order births rather than first or second births.

Teen birth rates remained relatively low in the 1970s and 1980s, despite large increases in the proportion of teenagers who were sexually active. The teen birth rate edged up around 1990. But, by 2020 increases in contraceptive use and a leveling of the share of teens who were sexually active helped reduce the teen birth rate to 15.3—the lowest level ever recorded in the United States.

Education and income also play a significant role in fertility. In nearly every contemporary society, people who are more educated and have higher incomes have fewer children than those who are less educated and have lower incomes.

In 2017, U.S. women ages 25 and older with an advanced degree had an average of 1.80 children, compared with 2.25 children for women with a high school diploma and 2.70 children for women without a high school diploma.¹⁰

Fertility Rates Are Falling Among Racial and Ethnic Minorities and Immigrants

In many countries, racial and ethnic minorities have higher fertility rates than the racial/ethnic majority. Often these differences arise from religious beliefs and cultural norms. Immigrants often maintain the childbearing patterns of their homelands when they arrive in a new country. For example, fertility rates for Arabs in Israel and Asians in Russia remain higher than average for the country. But over time, immigrants and their children tend to incorporate the fertility patterns of their adopted country.

In the United States, fertility rates have fallen since 1990 among all major racial/ethnic groups, declining fastest among African Americans and Latinas. In 2019, the TFR was 1.61 children per woman for non-Hispanic white women, compared with 1.51 for Asian women, 1.78 for African American women, and 1.94 for Latinas.¹¹