What Pregnancy Does to Your Brain

December 21st 2016

Laura Donovan

Having a baby is a life-changing experience, and new research published in the journal Nature Neuroscience suggests that may also change your brain.


Researchers looked at a sample of 25 women who were looking to become pregnant for the first time, and after comparing before-pregnancy and after-birth brain scans, they observed brain changes several months after the women gave birth. (Some of the changes were still present two years later, according to the New York Times.)

The researchers also looked at the brain scans of a group of 20 women who were not pregnant.

In these two groups, the women in the study who became pregnant lost gray matter. The Merriam-Webster dictionary defines gray matter as "neural tissue especially of the brain and spinal cord that contains nerve-cell bodies as well as nerve fibers and has a brownish-gray color." (New fathers and men who aren't fathers were also tested but showed no gray matter changes in their scans.) The research found that the changes can go on for at least two years after giving birth.

So what's behind this change in gray matter for new mothers?

Paul Thompson, a neuroscientist at the University of Southern California who did not work on the study, offered three possible explanations to The New York Times:

  • “The most intuitive is that losing gray matter is not beneficial, that later on there may be negative consequences."
  • This is a function of the “stress, diet, lack of sleep” that commonly accompany pregnancies and new parenthood.
  • This could be “part of the brain’s program for dealing with the future" and [increased pregnancy hormones may create] “pruning or cellular adaptation that is helpful," and possibly helping mothers specialize in “nurturing to extra vigilance to teaching.”

"The study strongly leans toward the third possibility," the Times explains.

The lead study author Elseline Hoekzema told The New York Times that it's important to note that gray matter loss "does not necessarily represent a bad thing" and that the researchers don't want to spread the notion that "pregnancy makes you lose your brain."

Kirstie Whitaker, a neuroimaging expert from Cambridge University, who didn't work on the study, told The Guardian that the gray matter loss could be a result of new mothers trying to understand their child's needs:

“It does make sense that a first time mother is going to have to work really hard to understand their baby’s needs. They have theory of mind anyway, they are adult women who are capable of empathizing with others, but this is a new stage, this is like another step up in terms of understanding how another being is seeing the world."

Whitaker added that even as the mothers lose gray matter, "they have actually have other cells come in to help reorganize and change up some of those connections to strengthen them, or at least make them more efficient."

Read the full New York Times piece on the study here.