“These areas are involved in a number of behaviors,” noted Dr. Kim Yonkers, a professor in psychiatry and obstetrics and gynecology at Yale School of Medicinewho was not involved in the new study. She explained some of these regions are involved in memory, while others are implicated in depression.
Changes in these areas may help women forget the pain or difficulty of pregnancy, suggested Yonkers.
Nearly identical reductions in gray matter were seen among the mothers who used fertility treatments as compared to those mothers who became pregnant naturally.
David Van Essen, co-principal investigator of the NIH’s Human Connectome Project, noted that there are other possible interpretations than gray matter volume changes. It could be an increase of myelin, he said, which could “masquerade” as gray matter volume change. Recent research suggests more myelin could speed conduction of nerve impulses in the brain.
“I think that an increase in myelin rather than a decrease in gray matter volume is a highly plausible alternative interpretation of their results,” said Van Essen, noting that no matter how the results are interpreted, “there is reasonably strong evidence that ‘something’ is different in the brains of postpartum women.”
Using the results
“At this point the results are associative,” said Yonkers, who noted the authors included “strong controls in the study including women who were not pregnant and men.” It remains unknown whether changes last beyond two years, she said, and “we don’t know what happens with multiple pregnancies.”
Overall, Yonkers, who has a long-standing interest in psychiatric disorders in women, finds the study “provocative.”
“Pregnancy is part of many women’s healthy lifestyle and it makes sense that it would confer benefits,” said Yonkers. She believes better understanding how the brain changes during pregnancy could lead to treatments for some medical conditions.
For instance, since attachment or connection was greater in women during pregnancy and postpartum, Yonkers speculated this knowledge might be applied to conditions where emotional response is poor — such as autism.
While the current study does not provide enough evidence for such treatments, Hoekzema observed that “in rats, it is known that some of the neural changes and the effects on maternal behavior can be simulated by administration of a regimen of hormones similar to pregnancy.”
According to Albert Einstein College of Medicine’s Wright, the small number of participants made it impossible for the researchers to accurately say whether the brain changes they observed might have been influenced by other factors, such as breastfeeding or stressors in the home related to pregnancy.
Still, based on changes in the teen brain associated with “hormonal surges” and changes in the menopausal brain tissue that follow a significant drop in estrogen, Wright said it “is not entirely surprising that pregnancy, which is also associated with rapid changes in estrogen levels, might also be associated with changes in brain tissue.”
The study is “exciting,” even if it “unfortunately leaves us with many questions,” Wright said. “There still is so much not yet known about the human brain.”