Pregnancies make you older – but only temporarily – in better health

Pregnancy increases a woman’s biological age, at least temporarily. A study by the US Yale School of Medicine suggests that those in the journal Cell Metabolism has appeared. However, the research group concluded that aging is not permanent: a few months after birth, the effect appears to reverse significantly – and in some cases to a surprising extent.

A woman’s body changes during a pregnancy full. The growing fetus shifts the organs in her abdomen, pelvic joints become looser, pregnancy hormones change appetite and energy levels, and even the neurons in the brain sometimes permanently rewire themselves. And not only that: Last year, a research group from the US Harvard Medical School also described that the stress of pregnancy can increase a woman’s biological age by up to two years. This biological age can be significantly different from the chronological age, which corresponds to the actual years of life: it is determined by our genes and by external influences, including lifestyle.

Stress is reflected in old age

A team led by perinatal researcher Kieran O’Donnell and biostatistician Hung Pham from the Yale School of Medicine now conducted a similar study with a larger group of test subjects. Specifically, the scientists analyzed blood samples from 119 women at various times during and after pregnancy.

They focused on so-called DNA methylations. These are tiny chemical modifications of the genetic material that – unlike DNA itself – can change over the course of a lifetime. These methylations form certain patterns that researchers can use to estimate a person’s biological age.

In fact, the research group found that the stress of pregnancy is reflected in the woman’s biological age: from early to late pregnancy, it increased by around two years over a period of around 20 weeks. This suggests that pregnancy accelerates aging, as work by Harvard Medical School had already shown. O’Donnell and his team were surprised when they determined the biological age of the women a few weeks after birth.

“Three months after birth, we found a remarkable decline in biological age, in some individuals by as much as eight years,” O’Donnell is quoted as saying in a statement. While pregnancy increases biological age, there is a clear and pronounced recovery in the period after birth, says the scientist.

Another result of the study is that a high body mass index in the mother before pregnancy has a negative impact on this recovery effect. In other words, women who were overweight before giving birth did not recover as significantly in biological age after giving birth. In contrast, breastfeeding resulted in a greater decline in maternal biological age within three months of birth.

According to O’Donnell, these observations offer interesting new impetus for aging research – although there are a few things to keep in mind: It is not clear whether the recovery effect after birth is relevant for the short- or long-term health outcomes of mothers, and whether these effects spread accumulated over several consecutive pregnancies. And O’Donnell cites a second unknown: “Similarly, we do not know whether the reduction in biological age after birth is simply due to the system recovering to the biological age before pregnancy, or, more provocatively, whether pregnancy has a rejuvenating effect.”