Summary: Pregnancy may accelerate biological aging in women. Using advanced epigenetic clocks that measure DNA methylation, researchers compared the biological age of women with different pregnancy histories to women who had never been pregnant. The study found that a greater number of pregnancies is associated with markers of accelerated biological aging in women.
This pattern did not appear in men from the same cohort, suggesting a biological cost specific to pregnancy and possibly breastfeeding. The findings point to an important gap in understanding how reproduction affects women’s long-term health and highlight the need for better support for young mothers, particularly in settings with limited resources.
Key facts:
- Women who reported having been pregnant showed epigenetic markers consistent with older biological age than women who had never been pregnant, and the effect increased with the number of pregnancies.
- The research used multiple epigenetic clocks—innovative tools that assess DNA methylation patterns—to detect signs of cellular aging in young adults.
- No comparable relationship between the number of pregnancies fathered and biological aging was observed in men, indicating the effect is linked to female reproductive physiology rather than shared social or behavioral factors.
Source: Columbia University
Pregnancy may carry a biological cost, according to a new study from the Columbia University Mailman School of Public Health.
The analysis, conducted among 1,735 young adults in the Philippines, shows that women who reported pregnancies appeared biologically older than those who had never been pregnant. Moreover, women with more pregnancies tended to show greater evidence of accelerated biological aging than women with fewer pregnancies.
Importantly, the number of pregnancies fathered by men in the same age cohort did not predict biological aging, implying that pregnancy itself—rather than the social or behavioral factors associated with parenting—may drive the observed changes in women.
The study appears in The Proceedings of the National Academy of Sciences (PNAS).
Previous epidemiological research has suggested that high fertility can be associated with negative effects on women’s health and longevity. What remained unclear was whether reproductive costs appear earlier in life, before chronic disease or age-related decline become evident. This study addresses that gap by applying molecular measures of aging to a young, high-fertility population.
One longstanding challenge has been reliably measuring biological aging in younger people. The researchers overcame this by using a suite of epigenetic clocks—tools that estimate cellular aging from DNA methylation (DNAm) patterns. These clocks capture different dimensions of cellular aging, health risk, and mortality-related processes, enabling researchers to study aging dynamics much earlier in life than traditional measures allow.
“Epigenetic clocks have transformed how we study biological aging across the life course and open new opportunities to identify when and how long-term health costs of reproduction and other life events emerge,” said Calen Ryan, PhD, the study’s lead author and an associate research scientist at the Columbia Aging Center.
Ryan emphasized that the findings indicate pregnancy may accelerate biological aging in young women. The study design is notable for following the same women over time, allowing the team to link increases in pregnancy count to changes in each woman’s epigenetic age.
The relationship between pregnancy history and epigenetic age remained after controlling for socioeconomic status, smoking, and genetic variation—factors known to influence biological aging. The absence of a comparable effect in men strengthens the interpretation that physiological aspects of pregnancy and postpartum processes contribute to the observed acceleration.
Ryan urged careful interpretation: many pregnancies recorded at baseline occurred during late adolescence, a period when women are still growing. Pregnancy during this phase may place extra strain on a young mother’s body, particularly when access to healthcare, nutrition, and social support is limited.
The authors also note that further research is needed to clarify how accelerated epigenetic aging detected in young adulthood will translate into long-term health outcomes or mortality decades later. Current knowledge about how epigenetic clocks predict health and longevity comes mainly from studies in North America and Europe; aging trajectories may vary across different populations and environments.
Ultimately, the study highlights potential long-term impacts of pregnancy on women’s biology and strengthens the case for policies and programs that support new parents—especially young mothers—in resource-constrained settings.
Co-authors include Christopher Kuzawa (Northwestern University); Nanette R. Lee and Delia B. Carba (USC–Office of Population Studies Foundation); Julie L. MacIsaac, David S. Lin, and Parmida Atashzay (University of British Columbia); Daniel Belsky (Columbia Public Health and Columbia Aging Center); Michael S. Kobor (University of British Columbia, Canadian Institute for Advanced Research, Centre for Molecular Medicine and Therapeutics).
Funding: The study was supported by the National Institutes of Health (R01AG061006), the National Science Foundation (BCS 1751912), and the University of British Columbia (UBC 60055724).
About this genetics, pregnancy, and aging research news
Author: Stephanie Berger
Source: Columbia University
Contact: Stephanie Berger – Columbia University
Image: The image is credited to Neuroscience News
Original research: The findings will appear in PNAS