The XX Factor

New Study Suggests Delayed Pregnancy Could Yield Kids With Stronger Cognitive Abilities

Waiting might be beneficial, depending on the circumstances.


Women in the U.S. continue to have children later and later in their lives, with the average woman approaching 30 for her first pregnancy. With more advanced motherhood has comes better average wages and educational levels for the mothers, alongside anxiety over riskier pregnancies. But a new study published in the International Journal of Epidemiology challenges the conventional wisdom that being an older mother is bad for the baby and indicates that, in a shift from previous research, children born to older mothers today may be more likely to perform well cognitively.

The study authors posit that the children of older mothers performed better because the mothers tended to be wealthier and more educated. The study, which divided women into age ranges of 25 to 29 and 35 to 39, found that the older women who gave birth in 2000–02 had children who performed better on tests. (The children were tested when 10 or 11 years old.) These studies are surprising when compared to similar studies done in 1958 and 1970, which found that children born to older mothers performed slightly worse. This study does not invalidate those studies but instead may point to changing educational and financial trends for women in the U.K., where the research was conducted.

More advanced maternal age is still associated with a greater chance of genetic defects, and having a first child over the age of 35 is associated with a higher risk of pregnancy complications. But these concerns focus on the health of babies before and at birth, not on their health and development afterward, which can become entangled with external factors. Cognitive ability, which includes problem solving and memory abilities, has been shown to be hampered by poverty. This may be because poorer families tend to experience more stress, while wealthier families can afford healthier food and proper medical care, as well as more time to spend with their children and the resources for books and educational toys and other forms of mental stimulation. It makes sense, then, that because older mothers tend to have greater resources, they could therefore also have children more likely to perform well on tests of cognitive function.

This research did not, however, account for race. As Elissa Strauss writes of the delayed motherhood trend, black women in the U.S., for instance, can’t always “count on a better, healthier, more financially stable future.”