What really happens to the brain during pregnancy?

We all know pregnancy changes your body (swollen feet, strange cravings, that famous glow), but what’s happening in your brain during all of this?

A 2024 study from UC Santa Barbara, published in Nature Neuroscience, offers a fascinating glimpse inside the pregnant brain, revealing it’s far more adaptable (and far less fragile) than many have assumed.

“We wanted to look at the trajectory of brain changes specifically within the gestational window,” explained lead author Laura Pritschet. While earlier studies compared brains before and after pregnancy, this research team did something new: they captured the brain in the act of transformation.

Tracking a first-time mother from pre-conception through to two years postpartum, the researchers scanned her brain every few weeks, like the world’s most dedicated neural paparazzi. The result? A high-resolution time-lapse of the pregnant brain as it rewires to prepare for the complex journey of parenthood.

So, what actually happens?

Well, for starters, the wrinkly outer layer of the brain, that’s the grey matter, actually shrinks during pregnancy. Sounds alarming? Not really. According to the researchers, this isn’t a loss so much as a “fine-tuning” of circuits, similar to what happens in teenage brains during puberty. In other words, the brain is getting leaner, meaner, and more specialised.

“This change could reflect another period of cortical refinement,” said the team, a kind of neural spring cleaning as the brain preps for motherhood.

At the same time, there is a noticeable increase in white matter, the tissue deeper in the brain that helps different regions communicate with one another. Interestingly, this growth peaks in the second trimester and diminishes just before birth – a finding that had never been observed before.

“The maternal brain undergoes a choreographed change across gestation, and we are finally able to see it unfold,” said Professor Emily Jacobs, the study’s senior author. This “dance” of brain changes hints at serious neuroplasticity, even well into adulthood.

It’s not just baby talk

Women’s brains during pregnancy have been unfairly stereotyped for ages – scatterbrained, emotional, fragile. But this study aims to dismantle that outdated idea. “Eighty-five percent of women experience pregnancy one or more times over their lifetime,” said Pritschet.

“This isn’t some fringe phenomenon – it’s fundamental to understanding the human brain.” And it could even hold clues for mental health. Since about one in five new mums experiences postpartum depression, the team hopes their findings will help improve early detection. “The more we learn about the maternal brain,” Pritschet added, “the better chance we’ll have to provide relief.”

What’s next?

With support from the Ann S. Bowers Women’s Brain Health Initiative, the researchers are expanding their work through the Maternal Brain Project. More mothers (and even their partners) are now being recruited across UC Santa Barbara, UC Irvine, and in Spain.

“Experts in neuroscience, reproductive immunology, proteomics, and AI are joining forces to learn more than ever about the maternal brain,” Jacobs said.

“Together, we have an opportunity to tackle some of the most pressing and least understood problems in women’s health.” So, the next time someone jokes about “pregnancy brain”, just tell them: actually, it’s a full-blown neurological glow-up.