Reproduction is thought to deplete the body’s ability for self-maintenance and repair, hastening the aging process. Studies demonstrating that women who have more children typically live shorter lives and experience worsening health as they age lend credence to this theory. It is challenging to research aging in younger people using simply sickness and mortality data, though, because aging in the body begins before we notice symptoms of age-related health issues.
A new study examines the relationship between reproductive history and biological aging. Scientists from the Columbia University Mailman School of Public Health conducted this study among 1735 young people in the Philippines.
It demonstrates that, compared to women who had never been pregnant, women who had reported having been pregnant appeared biologically older, and women who had reported being pregnant more frequently appeared biologically older than those who had not reported being pregnant. Interestingly, among men in the same age cohort, the number of pregnancies fathered did not correlate with biological aging. This suggests that there is a specific aspect of pregnancy or breastfeeding that promotes biological aging.
This study extends earlier findings that having a large number of children can be detrimental to a woman’s health and life expectancy. It was previously unknown whether these detrimental impacts of reproduction manifested themselves earlier in life, before the onset of age-related disorders. Measuring how quickly people age when they are young has proven to be one challenge.
This issue was resolved by employing novel techniques that assess DNA methylation (DNAm) to investigate various facets of aging, health, and mortality risk. With the aid of these instruments, sometimes referred to as “epigenetic clocks,” researchers can better understand how aging occurs at an earlier stage of life.
Calen Ryan, Ph.D., an associate research scientist in the Columbia Aging Center and lead author, said, “Epigenetic clocks have revolutionized how we study biological aging across the life course and open up new opportunities to study how and when long-term health costs of reproduction and other life events take hold.”
“Our findings suggest that pregnancy speeds up biological aging and that these effects are apparent in young, high-fertility women. Our results are also the first to follow the same women through time, linking changes in each woman’s pregnancy number to changes in her biological age.”
Even after accounting for several additional variables linked to biological aging, including smoking, socioeconomic level, and genetic variation, the relationship between biological age and pregnancy history remained. However, it did not exist among men from the same population. According to Ryan, this research suggests that having children has a role in biological aging, as opposed to cultural variables linked to early sexual engagement or fertility.
Ryan said, “Despite the striking nature of the findings, readers are recommended to remember the context: Many of the reported pregnancies in our baseline measure occurred during late adolescence when women are still growing. We expect this kind of pregnancy to be particularly challenging for a growing mother, especially if her access to healthcare, resources, or other forms of support is limited.”
Ryan said that our current understanding of epigenetic clocks and how they predict health and mortality comes mainly from North America and Europe but that the aging process can take slightly different forms in the Philippines and other places around the world.
“Ultimately, I think our findings highlight the potential long-term impacts of pregnancy on women’s health and the importance of taking care of new parents, especially young mothers.”
Journal Reference:
- Calen P. Ryan, Nanette R. Lee, Delia Carba et al. Pregnancy is linked to faster epigenetic aging in young women—Proceedings of National Academy of Sciences. DOI: 10.1073/pnas.2317290121