How Pregnancy Changes A Woman's Brain Structure

If you know any new parents (or you are one!), you’re already well aware that parenthood changes nearly every aspect of a person’s life. But new research suggests that, for new moms, this change happens even on a neurological level. A recent study found that pregnancy changes women’s brain structures for extended periods of time — at least two years, in fact. Researchers believe that these long-lasting neurological changes may contribute to the way new moms raise their babies.

For a study published Monday in Nature Neuroscience, Spanish and Dutch researchers used brain scans to compare the brains of new parents to those of people who haven’t had children. They took MRIs of 25 new mothers both before and after pregnancy and compared them with the scans of 20 women who had not been pregnant. They also looked at the brains of new fathers, comparing the MRIs of 19 first-time dads with 17 scans of childless men.

The researchers found that first-time moms had undergone significant changes in their brains, changes that made them distinct from people without children. Study co-author Elseline Hoekzema told The Guardian, “These changes were remarkably consistent. So consistent that a computer algorithm could automatically identify which of the women in our sample had been pregnant between the sessions and which [had] not.”

First-time mothers consistently exhibited a decrease in volume of gray matter in certain areas of the brain. “Decrease in gray matter” sounds scary, but in this case, the researchers believe that it may be a good thing, a process of refining certain areas of the brain to make them more efficient. (As Science News points out, teenagers undergo something similar, in which the volume of gray matter in their brains is pared down as their brains mature).

Hoekezema emphasized that her and her colleagues’ “findings do not suggest any link to changes in general cognitive abilities or intelligence.” Rather, the new moms lost gray matter in regions of the brain that are important to their “theory of mind network,” i.e. the regions of the brain that contribute to a person’s ability to imagine the mind of another person, a capacity central to empathy and to seeing other people’s points of view. The researchers suspect that the decrease in gray matter in these areas indicates a refinement (and therefore an improvement) of these abilities. “[O]ur findings suggest that there may be an evolutionary purpose to these changes that may serve you in some way when you become a mother,” Hoekzema told The Guardian. You don’t have to be a scientist to see how having an improved or more efficient ability to imagine the minds of other people could be beneficial to a woman caring for a new baby.

Among the study’s participants, these changes in the brain appeared to only occur among women. When the researchers compared the brains scans of new dads with those of men without children, they didn’t find the change in gray matter that they found with new moms. The researchers suggest that the neurological changes that women experience after pregnancy are thus biological, rather than the result of social or psychological change. It’s not clear what, exactly, is responsible for the changes that occur in women’s brains after giving birth, though the researchers suggest that the extreme hormone fluctuations that women undergo during and immediately after pregnancy may have something to do with it.

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