Many of us have heard expecting women complain of “pregnancy brain,” or a feeling of hazy forgetfulness. A new study found that these women may be on to something, and in fact, pregnancy creates brain alterations that can last up to two years.
Published in the journal Nature Neuroscience, the study found that pregnancy changes the size and structure of parts of the brain that deal with perceiving the feelings and perspectives of other people. The team of scientists from Spain and the Netherlands compared brain scans of women taken before they had ever conceived and after they had given birth for the first time. Per the New York Times:
The results were remarkable: loss of gray matter in several brain areas involved in a process called social cognition or “theory of mind,” the ability to register and consider how other people perceive things.
The study examined 25 women in their 30s in Spain over the span of five years. Each of the women had never conceived before but hoped to get pregnant. Scientists took brain scans before they conceived, and just a few months after giving birth. Most of the study participants were recruited from a fertility clinic, including 16 of whom conceived after fertility treatments. The team also compared scans of 20 women who also had never conceived but were scanned twice.
Only the pregnant women were found to have gray-matter reduction in the social cognition area of the cortex. In fact, the changes were “so clear” that the scans alone could show that a woman had been pregnant. Additionally, by comparing the scans of women who received fertility treatments to nine pregnant women who didn’t, the scientists found that fertility treatments don’t cause any differences in brain changes.
Most of the brain changes remained in place for at least two years, until the children were toddlers. The scientists also found that mothers who lost more gray matter tended to be more emotionally attached to their baby.
The study noted that additional research should examine a larger group of women and further assess social cognition in women, to see whether the brain changes actually have an effect on mothering. However, Dr. Ronald E. Cahl of the University of California, Berkeley, who wasn’t involved in the study, told the Times that the finding that brain changes can enhance a woman’s maternal instinct is “provocative, and I think it’s likely to be true.”