SUNDAY, Dec. 27, 2015 (HealthDay News) -- Women who have their first child in their mid-20s to mid-30s have better health at age 40 than those who have their first child in their teens or early 20s, a new study finds.
Researchers looked at data from more than 3,300 American women for the study. The women's health was followed from 1979 through 2008. The women all had a first child between ages 15 and 35. They rated their own health when they were 40 years old.
At that age, those who had their first child between ages 25 to 35 reported better health than those who had their first child at ages 15 to 19, or 20 to 24. There were no significant health differences at age 40 between women who had their first child in their teens or early 20s.
While the study found an association between early childbirth and worse health at 40, it wasn't designed to prove a cause-and-effect relationship.
The findings were published in the December issue of the Journal of Health and Social Behavior.
"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," lead author Kristi Williams, an associate professor of sociology at Ohio State University, said in a journal news release.
The finding that the mid-life health of women is the same for women who had their first child in their teens or early 20s challenges a common belief that it's better to wait at least until your early 20s to give birth.
The researchers also disproved another widely held assumption: that unmarried women who have children will be healthier if they eventually get married. Instead, the study showed that when single black mothers later married, they had worse health at age 40 than those who stayed single.
However, the study couldn't say why this was so. But the researchers said their findings suggest that public health efforts to encourage single mothers to marry may have unintended consequences.
"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," Williams said.
In the United States, about one-third of all first births occur in women aged 20 to 24, the research showed. In most cases, these women are single, the researchers said.
"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," Williams said.
The U.S. Food and Drug Administration has more on women's health.