Pregnancy Alters Almost Every Brain Region

A new study published in Nature Neuroscience provides one of the first comprehensive maps of how the human brain changes during pregnancy. These findings hint at broader implications for maternal health, parenting behaviors and brain aging.

Identifying neurological changes during pregnancy

Each year, around 140 million women become pregnant. Over the gestational period, the body goes through several physiological changes, driven by complex hormonal shifts that prepare a woman for motherhood. Although many of these changes are well documented, such as weight gain, metabolic adjustments and increased blood flow, little is known about how pregnancy affects the brain.

Previous studies in humans have identified changes in the brain following pregnancy, including reductions in gray matter volume in postpartum women. However, the specific neurological changes that unfold during pregnancy itself remain largely unknown.

“Previous studies had taken snapshots of the brain before and after pregnancy, but we’ve never witnessed the brain amid this metamorphosis,” said corresponding author Dr. Emily Jacobs, an associate professor at the University of California, Santa Barbara.

Tracking brain changes from pre-conception to postpartum

Pregnancy-related brain changes were assessed in a healthy 38-year-old primiparous woman through a series of magnetic resonance imaging (MRI) scans over 3 years. The participant had 26 scans and blood evaluations in total; beginning from 3 weeks pre-conception (4 scans), throughout all trimesters of pregnancy (15 scans) and up to 2 years postpartum (7 scans). The scans were compared to brain changes seen in eight non-pregnant controls from the Day2day dataset, two of which were male.

“Using a precision imaging approach, we were able to observe sweeping changes in gray matter volume, cortical thickness, white matter microstructure and ventricle volume as it all unfolded week by week,” said Jacobs.

“Over 80% of the brain regions we studied had reductions in gray matter volume,” added co-author Dr. Elizabeth Chrastil, an associate professor at the University of California, Irvine.

Decreases in cortical volume and thickness could be observed by the ninth week of pregnancy, particularly in regions such as the default mode network, which is associated with social cognition. Many of these changes were still present up to two years postpartum.

Some dynamic changes were specific to the gestational period. Notably, large increases in white matter microstructure were observed during the first and second trimesters of pregnancy, though these levels returned to baseline by the time of the first postpartum scan.

Potential implications for maternal brain health

Although this research only follows a single case study, the results provide the first comprehensive data on the neurological changes that occur during pregnancy.

“It seems like the maternal brain undergoes this choreographed change across gestation and we’re finally able to observe the process in real time,” said Jacobs.

The study may also have potential implications for maternal health. Considering one in five women experience perinatal mental health conditions, increasing our understanding of the brain changes that occur are vital for early detection.

“Scientists don’t have the data we need to predict postpartum depression before it manifests. We don’t have the data we need to understand the effects of preeclampsia on later-life brain health. We need better data,” said Jacobs.

Further investigations are needed to be able to generalize the findings to a broader population, however, the study lays the groundwork for a greater understanding of the neural structural changes during pregnancy.

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

This article is a rework of a press release issued by Springer Nature. Material has been edited for length and content.