Pregnancy initiates significant transformations within a woman’s body, affecting various systems including hormonal, cardiovascular, respiratory, gastrointestinal, and urinary systems. Furthermore, recent research highlights that the brain also experiences substantial changes—some of which are temporary while others have lasting effects.
On Monday, researchers announced a groundbreaking study that for the first time charts the neurological shifts that occur as a woman’s brain adapts to pregnancy. This research was based on a series of scans conducted 26 times, beginning three weeks prior to conception, continuing through all nine months of pregnancy, and extending into two years post-delivery.
The findings indicated a notable reduction in the volume of cortical gray matter—the wrinkled outer layer of the brain—alongside an increase in the microstructural integrity of the white matter situated deeper in the brain. These transformations were linked to rising levels of the hormones estradiol and progesterone. Gray matter consists of the cell bodies of neurons, while white matter comprises bundles of axons, which are elongated fibers responsible for long-distance signal transmission within the brain.
This pioneering study focused on a single participant: Elizabeth Chrastil, a cognitive neuroscientist at the University of California, Irvine, who was a first-time mother at the time of the research and has since given birth to a healthy boy, now four and a half years old.
Chrastil, who was 38 during the study and is now 43, noted that researchers have since observed similar patterns in several other pregnant women involved in an ongoing initiative known as the Maternal Brain Project, with the goal of increasing the number of participants to the hundreds.
“It’s rather surprising that even in 2024, we have so little understanding of the brain’s dynamics during pregnancy,” commented Chrastil. “This research not only raises more questions than it answers, but also indicates that we are merely beginning to explore this complex topic.”
The imaging studies revealed an approximate 4% decrease in gray matter across about 80% of the brain regions analyzed. While there was a slight recovery in gray matter volume after childbirth, it did not revert to the levels observed before pregnancy. Conversely, the scans indicated a 10% increase in the microstructural integrity of white matter, which reflects the health and quality of neural connections. This peak occurred late in the second trimester and early in the third trimester, eventually returning to pre-pregnancy levels after delivery.
Emily Jacobs, a neuroscientist at the University of California, Santa Barbara and the study’s senior author, remarked, “The maternal brain experiences a beautifully coordinated transformation throughout pregnancy, and we are finally able to witness this process in real-time.” Unlike previous research that captured static images of the brain before and after pregnancy, this study has provided a unique glimpse into the brain’s dynamic changes during this significant period.
The researchers emphasized that the reduction in gray matter may not necessarily be detrimental. Laura Pritschet, a postdoctoral fellow at the University of Pennsylvania and the lead author of the study, explained, “This transformation might represent a refinement of brain circuits, similar to what occurs in young adults during puberty when their brains become more specialized. Additionally, some observed changes could also be a response to the intense physiological demands of pregnancy, highlighting the brain’s remarkable adaptability.”
Looking ahead, the researchers aspire to investigate how variations in these brain changes might aid in predicting conditions such as postpartum depression, as well as the impact of preeclampsia—a serious pregnancy-related blood pressure complication—on brain function. Participant Chrastil shared that she was unaware of the changes in her brain during the study and did not perceive any significant difference in her mental state. “Reflecting on it now, I can say, ‘Wow, that was quite a journey,'” Chrastil noted. She acknowledged the concept of “Mommy Brain,” which describes the mental fog that some expectant mothers experience, adding, “But personally, I didn’t really feel any of that.”
