Study Reveals Brain Reorganization in Women During Pregnancy, According to Reuters

By Will Dunham

WASHINGTON – Pregnancy induces significant transformations in a woman’s body, affecting hormonal, cardiovascular, respiratory, gastrointestinal, urinary systems, and more. A recent study highlights that the brain also experiences considerable changes, some temporary and others more lasting.

For the first time, researchers have mapped the neurological changes that occur during pregnancy, conducting brain scans 26 times beginning three weeks before conception, throughout the nine months of pregnancy, and extending to two years postpartum.

The study revealed a notable decrease in the volume of cortical gray matter—the brain’s outermost layer—alongside an increase in the structural integrity of white matter located deeper within the brain. These modifications were linked to rising levels of the hormones estradiol and progesterone.

Gray matter consists of the cell bodies of nerve cells, while white matter is made up of the axons—the long, thin fibers that transmit signals between different brain regions.

This pioneering research focused on a single participant: Elizabeth Chrastil, a cognitive neuroscientist from the University of California, Irvine, and co-author of the study, who gave birth to a healthy boy now aged 4. Chrastil was 38 years old during the study and is currently 43.

The scientists have since observed similar patterns in several other pregnant women participating in an ongoing study known as the Maternal Brain Project, with plans to expand the sample size into the hundreds.

"It’s surprising that in 2024 we have so little knowledge about what happens in the brain during pregnancy. This research opens up more questions than it answers, and we are just beginning to explore them," Chrastil noted.

The scans indicated an average reduction of approximately 4% in gray matter across about 80% of the brain regions examined. Although there was a slight rebound in gray matter postpartum, it did not return to pre-pregnancy levels. Conversely, the integrity of white matter increased by about 10%, peaking late in the second trimester and early in the third trimester, before reverting to pre-pregnancy conditions after childbirth.

"The maternal brain undergoes a carefully coordinated transformation throughout gestation, and we are now able to observe this process in real time," said Emily Jacobs, a neuroscientist from the University of California, Santa Barbara, and senior author of the study published in a leading journal.

"Previous research only captured snapshots of the brain before and after pregnancy, but this study allows us to witness the brain’s metamorphosis," she added.

Researchers are unsure whether the reduction in gray matter is detrimental.

"This change may indicate a fine-tuning of brain circuits, similar to the specialization observed in young adults transitioning through puberty. Some changes we observed could also be responses to the physiological demands of pregnancy, illustrating the brain’s adaptability," said Laura Pritschet, a postdoctoral scholar from the University of Pennsylvania and lead author of the study.

In the future, the researchers aim to investigate how variations in these neurological changes might help predict issues such as postpartum depression, as well as the effects of preeclampsia—a serious blood pressure condition that can develop during pregnancy—on brain health.

Chrastil, during the study, was unaware of the findings regarding her brain changes and reported that she did not feel any different.

"And so, you know, now there’s some distance to be able to say, ‘OK, well, that was a wild ride,’" Chrastil reflected.

She also noted, "Some people talk about ‘Mommy Brain’ and similar experiences," referring to the mental fog some pregnant women report, "but I didn’t really experience any of that."