Childbirth reversed women's biological aging

Pregnancy causes significant physiological stress to the body of the expectant mother, so it has repeatedly been linked to biological aging. Now medical researchers have discovered what reverses this process.

Gynecologists, obstetricians, reproductive and pediatricians from Yale School of Medicine and the University of California (USA) using epigenetic clock - a series of DNA markers - obtained estimates of biological aging in women during pregnancy and after childbirth. The results of the study are published in the journal Cell Metabolism.

Pregnancy, which comes with a lot of physiological stress, is considered a natural test for a woman's body that can reveal hidden problems. It also correlates with an acceleration of biological aging, as proven by the authors of a 2023 scientific paper that studied mice. This is confirmed by the indicators of epigenetic clock - a set of epigenetic DNA tags that allow to determine the biological age of a tissue or organ. In turn, biological age is the best predictor of health problems, such as cardiovascular disease and dementia.

Now a team of American doctors has expanded on the findings of their colleagues. They studied blood samples taken from 119 women in early, middle and late pregnancy. The last samples were given to 68 participants about three months after delivery. Using these data, the researchers were able to estimate the rate of biological aging in women based on the main components of the epigenetic clock - the methyl tags PCHorvath1, PCPhenoAge and PCGrimAge.

Then, using generalized additive models, the authors tested whether gestational age is associated with accelerated biological aging and whether these effects are reversed after birth. The models also took into account the birth mother's age, ethnicity, education level, family income, body mass index before conception, and more.

As a result, the researchers found a link between gestational age and biological age. Around the 18th week of expecting a baby, measures of the mother's adjusted biological age increased by 2.39 years for PCPhenoAge, 1.19 years for PCGrimAge, 2.52 years for GrimAge2, and 0.07 years for PACE.

"We also observed a statistically significant 'reversal' of biological aging across all epigenetic biomarkers starting late in pregnancy and up to about three months postpartum," the paper's authors added. The change was unexpectedly dramatic: some women became biologically younger compared to the start of pregnancy - sometimes by as much as eight years.

That is, although pregnancy accelerated biological aging, the postpartum period was accompanied by a clear recovery. However, it was not the same for everyone: it turned out that participants who were on the verge of obesity before pregnancy lost fewer years of biological age in the three months after childbirth than women with a normal BMI. At the same time, mothers who exclusively breastfed their infants had a greater decrease in biological age than those who introduced formula milk into the baby's diet.

In the future, the researchers plan to investigate whether changes in the biological age of the birthing woman persist over time and whether such effects accumulate in subsequent pregnancies.

"Similarly, we don't know whether the postpartum decline in biological age can be considered simply the result of its recovery to its pre-pregnancy state or, more provocatively, whether pregnancy may have a rejuvenating effect," summarized Kieran O'Donnell, one of the paper's authors.