The nine months of pregnancy cause profound and lasting changes in women’s brains, particularly under the influence of sex hormones. A new study reveals that these changes persist well beyond childbirth.
For a long time, the impacts of pregnancy on women’s brains remained a mystery. But a study published in “Nature Neuroscience” changed the game by delivering unprecedented results.
Researchers observed changes in a woman’s brain during 26 MRI scans before, during and after her pregnancy, revealing significant brain remodeling.
Hormones at the heart of transformations
Sex hormones, such as estrogen and testosterone, play a crucial role in regulating brain functions such as mood or memory. During pregnancy, these hormones undergo significant fluctuations that directly impact the brain.
Jacobs and his team, who initiated the “28andMe” project, were interested in brain changes during menstrual cycles. They extended their study to pregnancy thanks to Liz Chrastil, a neuroscientist at the University of California, who agreed to participate in the experiment by undergoing several MRI scans during her own pregnancy.
This study made it possible to follow in detail the evolution of the brain over the months.
Loss of gray matter: a positive adaptation
Pregnancy causes a decrease in gray matter, the outer layer of the brain involved in cognition and learning. This observation may seem alarming, but the decrease in gray matter is actually a form of adaptation.
This process is comparable to that of adolescence, another period of hormonal upheaval. These changes, far from being a sign of decline, would aim to make the brain more efficient by refining neuronal processing.
The researchers found that the loss of gray matter, which begins in the first weeks of pregnancy, stabilizes at delivery and persists for years afterward. This remodeling is linked to the increase in the hormones estradiol and progesterone, and affects more than 80% of brain regions.
The scope of these changes, as well as their long-term effects, remain to be clarified.
A temporary strengthening of white matter
In addition to gray matter, pregnancy also affects the brain’s white matter, which is made up of nerve fibers that facilitate communication between neurons. Researchers observed a strengthening of this matter during the second trimester, before it returned to its initial state after birth.
In adolescents, similar changes have been associated with improved cognitive abilities, but the implications for mothers are still unclear.
Essential research for women’s health
This study is just the beginning. Other pregnant women are now participating in the experiment, and the team hopes to better understand the pace of normal brain changes during pregnancy.
These data could ultimately make it possible to identify early signs of perinatal depression, which affects 10 to 20% of women, by measuring deviations from usual brain transformations.
Thanks to initiatives like the Ann S. Bowers Women’s Brain Health Initiative, research into the effects of pregnancy, menopause, and hormone therapy is advancing. These studies aim to expand scientific knowledge beyond the specifics of the male body, which has long been the focus of research.
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