Women “age” during pregnancy, but become “younger” after giving birth.

With each birth, our age inevitably increases. But this is not the case for our biological age, a mirror of our physical health that fluctuates through life events. Among these impactful experiences are pregnancy and childbirth. That’s according to a letter from researchers at Yale School of Medicine, the University of California, and the Max Planck Institute for Psychiatry in Munich, published March 22 in the journal Cell Metabolism and referred to as The world . Their work highlights the effects of pregnancy on biological aging and, subsequently, breastfeeding on rejuvenation.

The researchers built on a previous study from Massachusetts General Hospital (a teaching hospital at Harvard Medical School) published in 2023. This research has already shown that certain physiological stresses lead to molecular aging, including certain diseases or surgeries, as well as pregnancy.

Rejuvenation from 3 to 8 years

To confirm these findings and determine whether pregnancy is associated with accelerated biological aging and whether these effects are reversed after delivery, researchers conducted a prospective cohort study within the Developmental, Health and Life Sciences Research Program at the University of California, Berkeley. “The data came from blood samples taken from 119 women during early, mid- and late pregnancy, as well as a fourth blood sample taken from 68 of those women approximately three months after delivery,” the study’s introduction reads.

Results? “Pregnancy is positively associated with biological aging,” the scientists say. In particular, the biological age of pregnant women can reach from 0.7 years to 2.52 years. The research team was also able to observe a “prominent reversal” of this age in the postpartum period. Their work actually shows a 3- to 8-year reduction in pregnancy and after. It is 2-3 times more than the age increase observed during pregnancy.

BMI and breastfeeding

The researchers identified the mother’s body mass index (BMI) and breastfeeding as two factors that may influence these variations during pregnancy and postpartum. Three months after giving birth, women who had a BMI of 30 (moderately obese) during pregnancy had a biological age of 0.7 to 1.4 years higher than those with a BMI of 23. Furthermore, “exclusively breastfeeding mothers had a mean biological age. approximately 1 year younger” than mothers who choose mixed or only formula for their child.

However, additional work will be needed to “determine whether the observed reversal in maternal biological age at three months postpartum persists over time and whether these effects accumulate over successive pregnancies,” the study authors conclude.