Pregnancy not only changes the body but also a woman’s brain

During pregnancy, a woman’s body goes through many changes – hormonal, cardiovascular, respiratory, digestive, urinary, and more. But what changes are made in the brain, hasn’t been well studied in humans.
New research, published in Nature Neuroscience, has shown that the brain also experiences significant changes, some of which are temporary, while others last longer.
For the first time, researchers have mapped these brain changes by conducting brain scans 26 times, starting three weeks before conception, continuing through the nine months of pregnancy, and two years after birth.
The study found that the brain’s outer layer, called the grey matter, decreased in volume, while the deeper white matter, which helps different parts of the brain communicate, became more structured.
These changes happened as levels of the pregnancy hormones, estradiol and progesterone, rose.
Grey matter contains the cell bodies of brain nerve cells, while white matter consists of long fibres that transmit signals across the brain.

Many white matter pathways in the brain show improvements as pregnancy progresses, with these changes becoming more noticeable around 36 weeks. This was found by analyzing brain scans taken over time. (Photo: Nature Neuroscience)

This study focused on just one subject: Elizabeth Chrastil, a neuroscientist and co-author of the study.
She was 38 years old when she participated and gave birth to a healthy boy, who is now four and a half years old.
Since then, scientists have seen the same pattern in other pregnant women as part of ongoing research known as the Maternal Brain Project, which aims to expand the study to hundreds of women.
“It’s surprising that even in 2024, we still know very little about how pregnancy affects the brain,” Chrastil said. “This study raises more questions than it answers, and we’re just beginning to explore them.”
The scans showed that, on average, grey matter volume dropped by about 4% in 80% of the brain regions studied. There was a small recovery after birth, but it didn’t return to pre-pregnancy levels.
White matter, on the other hand, showed a 10% improvement in structure, peaking in the late second and early third trimesters, before returning to pre-pregnancy status after birth.

The scans showed that, on average, grey matter volume dropped by about 4% in 80% of the brain regions studied. (Photo: Getty Images)

Previous research had only compared brain scans from before and after pregnancy, but this is the first time scientists have been able to observe the brain changing throughout pregnancy.
It’s still unclear if the reduction in grey matter is harmful.
“It could be that the brain is fine-tuning itself, much like what happens during puberty when the brain becomes more specialised,” said Laura Pritschet, lead author of the study. “Some of these changes could also be a response to the physical demands of pregnancy, showing how adaptable the brain can be.”
Chrastil, who didn’t feel any different during the study, reflected on the experience: “It’s interesting to look back now and think, ‘That was a wild journey.’”
She also mentioned that she didn’t experience the “Mommy Brain” that some women describe, referring to mental fog during pregnancy.