Timing of first childbirth influences women's health at age 40

Researchers found that women who had their first child in their early 20s didn't report better health at midlife than those who had their first baby as a teen.

"We've had all this focus on the bad effects of teen childbearing and never really asked what happens if these teens waited to early adulthood," said Kristi Williams, lead author of the study and associate professor of sociology at The Ohio State University.

"The assumption has been that 'of course, it is better to wait.' But at least when it comes to the later health of the mother, that isn't necessarily true."

The study also counters another common assumption: that women who have a baby outside of marriage will be healthier if they get married.

In fact, the study found that single black women who had a child and later married actually reported worse health at midlife than those who had a baby but stayed single.

This result suggests that public policies encouraging marriage among single mothers may have some unintended negative consequences, Williams said.

"Most studies indicate that marriage promotion efforts have been unsuccessful in increasing marriage rates. Our findings suggest that may be a good thing, at least for black women's health," she said.

The study appears in the December 2015 issue of the Journal of Health and Social Behavior. Williams co-authored the study with Sharon Sassler of Cornell University; Fenaba Addo of the University of Wisconsin-Madison; and Adrianne Frech of the University of Akron.

The study used data from 3,348 women who participated in the National Longitudinal Survey of Youth 1979 (NLSY79) and who were interviewed every one or two years from 1979 through 2008. All the women had a first birth between the ages of 15 and 35. They all rated their own health at age 40 on a scale from poor to excellent.

The NLSY79 is conducted by Ohio State's Center for Human Resource Research for the U.S. Bureau of Labor Statistics.

The researchers compared women who had their first birth as teens (ages 15-19), during early adulthood (ages 20-24) and when they were older (ages 25-35).

Results showed that women who were age 25 to 35 when they had their first birth also tended to report better health at age 40 than the two younger groups.

But there was no significant difference in midlife health for those with teen births compared to those who waited until they were age 20 to 24.

"Ours is the first U.S. study to find that having your first child in young adulthood is associated with worse self-assessed health decades later for white and black women, when compared to those who wait until they are over 24," Williams said.

In general, women who were married when they had their first child reported better health at age 40. Perhaps the most interesting results had to do with what happened to single women who had babies.

For black women, those who never married after having a child outside of marriage had better self-rated health than those who did later marry.

This study can't say why, Williams said. But other research suggests that many black single mothers face a lack of eligible men who have good economic prospects. Those who do marry are likely to have a spouse who doesn't have a high school education and doesn't have a good job.

"That can lead to stress and conflict in marriage, which can result in poorer health for the women as they age," she said.

Williams noted that this study was done with a particular cohort of women -- those born in the early 1960s -- and some factors have changed for women who grew up later.

Still, given these findings, today's demographics give cause for concern.

In the United States today, about one-third of all first births occur in the 20 to 24 age group, and most of these births are to single mothers, according to a recent National Vital Statistics Report. The proportion of black women having a teen birth has declined significantly, but 63 percent of all first births to black women still occur among those age 24 or younger.

"We still need to be concerned that women who are having births in their early 20s may face more health challenges as they reach middle age than those who wait longer," she said.

This research was supported by a grant from the National Institute of Child Health and Human Development.