Can Pregnancy Transform a Woman's Brain? A Nature Neuroscience Study Highlights - Video

A new study has revealed that the brain undergoes major changes during pregnancy, some fleeting and others more enduring.

Researchers, for the first time, have mapped the changes that unfold as a woman's brain reorganizes in response to pregnancy, based on scans carried out 26 times starting three weeks before conception, through nine months of pregnancy and then two years postpartum.

The study documented a widespread decrease in the volume of cortical gray matter as well as an increase in the microstructural integrity of white matter located deeper in the brain. Both changes coincided with rising levels of the hormones estradiol and progesterone.

The scientists said that since the study's completion they have observed the same pattern in several other pregnant women who have undergone brain scans in an ongoing research initiative called the Maternal Brain Project. They aim to expand the number into the hundreds.

"It's pretty shocking that in 2024 we have hardly any information about what happens in the brain during pregnancy. This paper opens up more questions than it answers, and we are just scratching the surface of these questions," Chrastil added.

The scans showed a reduction averaging about 4% in gray matter in roughly 80% of the brain regions studied. A small rebound postpartum did not return the volume to pre-pregnancy levels. The scans also showed an increase of about 10% in white matter microstructural integrity, a measure of the health and quality of the connections between brain regions, peaking late in the second trimester and early in the third trimester, then returning to pre-pregnancy status postpartum.

"The maternal brain undergoes a choreographed change across gestation, and we are finally able to observe the process in real time," said University of California, Santa Barbara neuroscientist Emily Jacobs, senior author of the study.

The researchers said it is not clear that the loss of gray matter is a bad thing.

"This change could indicate a fine-tuning of brain circuits, not unlike what happens to all young adults as they transition through puberty and their brain becomes more specialized. Some changes we observed could also be a response to the high physiological demands of pregnancy itself, showcasing just how adaptive the brain can be," University of Pennsylvania postdoctoral scholar and study lead author Laura Pritschet said.

Reference: Pritschet, L., Taylor, C.M., Cossio, D. et al. Neuroanatomical changes observed over the course of a human pregnancy. Nat Neurosci (2024). https://doi.org/10.1038/s41593-024-01741-0