Pregnancy may speed up biological ageing in women, a study has found.
Scientists at the Columbia University Mailman School of Public Health in New York looked at the reproductive histories and DNA samples from 1,735 people in a long-term, continuing health survey in the Philippines to investigate the influence pregnancy has on the ageing process.
They worked out participants’ biological age using six different “epigenetic clocks” – genetic tools that estimate biological age based on patterns of a process called DNA methylation.
The study involving 825 young women found that each individual pregnancy a woman reported was linked with an additional two to three months of biological ageing, and women who reported being pregnant more often during a six-year follow-up period showed a greater increase in biological ageing during that period.
The relationships between pregnancy and biological ageing persisted even when the authors accounted for socioeconomic status, smoking, genetic variation and the built environment in participants’ surroundings.
The authors failed to find a link between increased biological ageing and the number of pregnancies fathered by 910 same-aged men from the same health survey.
The findings are published in the Proceedings of National Academy of Sciences.
Calen Ryan, the lead author of the study and an associate research scientist in the Columbia Aging Center, said: “Our findings suggest that pregnancy speeds up biological ageing, 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.”
Ryan emphasised 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.”
He added: “We still have a lot to learn about the role of pregnancy and other aspects of reproduction in the ageing process. We also do not know the extent to which accelerated epigenetic ageing in these particular individuals will manifest as poor health or mortality decades later in life.”