Research shows that pregnancy accelerates biological aging in a healthy, young adult population

Pregnancy can come at a cost, reports a new study from the Columbia University Mailman School of Public Health. The study, conducted among 1,735 young people in the Philippines, found that women who reported being pregnant looked biologically older than women who had never been pregnant, and that women who were pregnant were more likely to look biologically older than women who reported fewer pregnancies.

Notably, the number of pregnancies conceived was not associated with biological aging among men of the same age, implying that it is something specifically about pregnancy or breastfeeding that accelerates biological aging. The findings are published in the Proceedings of the National Academy of Sciences.

This study builds on epidemiological findings that high fertility can have negative side effects on women’s health and longevity. What was not known, however, was whether the reproductive costs were present earlier in life, before disease and age-related decline became apparent.

Until now, one of the challenges has been to quantify biological aging among young people. This challenge was overcome by using a collection of new tools that use DNA methylation (DNAm) to study different facets of cellular aging, health and mortality risk. These tools, called “epigenetic clocks,” allow researchers to study aging earlier in life, filling an important gap in the study of biological aging.

“Epigenetic clocks have revolutionized the way we study biological aging across the lifespan and provide new opportunities to study how and when the long-term health costs of reproduction and other life events manifest,” said Calen Ryan Ph.D. ., lead author of the book study and associate professor at the Columbia Aging Center.

“Our findings suggest that pregnancy accelerates biological aging, and that these effects are evident in young, highly fertile women,” says Ryan. “Our results are also the first to follow the same women over time, linking changes in each woman’s pregnancy rate to changes in her biological age.”

The relationship between pregnancy history and biological age persisted even after several other factors related to biological aging were taken into account, such as socioeconomic status, smoking, and genetic variation, but it was not present in men from the same sample. This finding, Ryan noted, points to some aspect of childbearing – rather than sociocultural factors related to early fertility or sexual activity – as the driver of biological aging.

Despite the striking nature of the findings, Ryan encourages readers to remember the context. “Many of the reported pregnancies in our baseline survey occurred during late adolescence, when women are still growing. We expect that this type of pregnancy will be particularly challenging for a growing mother, especially if her access to health care, resources or other forms of support is limited.”

Ryan also acknowledged that there is still more work to be done: “We still have a lot to learn about the role of pregnancy and other aspects of reproduction in the aging process. We also do not know to what extent accelerated epigenetic aging in these specific individuals will manifest itself as poor health or mortality decades later in life.”

Ryan said that our current understanding of epigenetic clocks and how they predict health and mortality comes largely from North America and Europe, but that the aging process may take slightly different forms in the Philippines and other places around the world.

“Ultimately, I think our findings highlight the potential long-term effects of pregnancy on women’s health, and the importance of caring for new parents, especially young mothers.”