Birth rate of women in the U.S. 1950-2020, by age

Over the past 70 years in the United States, women have gradually started having children at a later point in their lives. Before the 1980s, women in their early twenties had the highest birth rates, however women in their late twenties had the highest rates between 1980 and 2015, but were recently overtaken by women in their early thirties. Another major trend is the decline of teenage pregnancies, which was less than a quarter of it's 1950-1955 rate in the years between 2015 and 2020. In fact, birth rates among 15-19 years olds often doubled birth rates of women aged 35-39 throughout the late twentieth century, but in 2020, the opposite is true.

For women in their forties, birth rates have remained comparatively lower than rates among the other age groups. The high figures in the 1950s and 1960s, can be attributed to the baby boom that followed the Second World War. In more recent decades, rising birth rates among older age groups is not only due to societal trends, but has also been aided by improvements in assisted reproductive technology (ART), such as in vitro fertilization (IVF). Such technologies have granted thousands of women the ability to conceive in circumstances where this would not have been possible in years past.