A new report is showing that despite declining fertility rates among US women, one group is continuing to grow: older women. The report showed that birth rates in US women dropped to 1.62 in 2023, down from 1.66 in 2022 and 2021. Also, for the first time, in 2023 there were more births from women over 40 than teens. The data tracks from 1990 to 2023 and reveals interesting and possibly problematic changes in the reproductive landscape of the US and globally.

According to the data, most births occur to women aged 30 to 34 when it used to be the greatest amongst women 25 to 29. While fertility rates of younger women and adolescents has continued to drop, rates of older women have skyrocketed. Rates amongst women ages 35 to 39 increased 71% while the rate for women ages 40 to 44 increased 127%. The reasons why women are delaying having children are numerous, including wider access to birth control, women choosing to focus more on education and careers, and technological advances in fertility. “All of those conditions shape when people want to start having children,” said Elizabeth Wildsmith, a family demographer and sociologist at Child Trends.

However, women waiting until they’re older may increase prenatal health problems.  Current studies suggest that higher maternal ages increase risks of complications like gestational diabetes, high blood pressure, preeclampsia, and miscarriage. Other complications include low birth weight and genetic disorders. Dr. Florencia Polite, chief of general obstetrics and gynecology at the University of Pennsylvania’s Perelman School of Medicine, pushed back at labeling all older women “high risk.” “The truth is, a lot of women from 35 to 40 are not really considered high-risk anymore,” she said, noting that women in their 40s and 50s require much more observation.

The rise of maternal age, however, has also coincided with a rise in maternal mortality, with the rate of maternal mortality in the U.S. in 2021 for women under 25 at 20.4 per 100,000 live births and 31.3 for women ages 25 to 39. That number, however, was much higher for women 40 and over at 138.5 per 100,000 births. Another risk is that the longer women put off having children, the higher likelihood they will have less than they wanted or none at all. Dr. Lisa Dunn-Albanese, an ob-gyn at Brigham and Women’s Hospital in Boston, says that is more concerning for her. “We might be settling into this new, lower fertility rate where people are waiting longer to have kids,” she said.