Revising Our Understanding of the Maternal Brain

Until the late 20th century, many believed the human brain was ‘hardwired’, much like a computer, with its neural connections remaining unchanged after adulthood. However, it turns out that this extraordinary organ can continue to adapt and evolve over time.

Interestingly, just like the different phases of Taylor Swift’s career, the brain goes through distinct major periods. Motherhood appears to play a significant role in this process.

In 2024, a group of neuroscientists in the US delivered the first comprehensive map of brain changes throughout a single pregnancy. They conducted brain scans on a woman at various points—before, during, and after her pregnancy. As she neared her due date, researchers observed a surprising reduction in certain areas of her brain.

This unexpected transformation sparked the initiation of the Maternal Brain Project (MBP). This initiative aims to unravel the complexities of brain alterations during motherhood, an area that hasn’t received much attention from experts.

According to neuroscientist Emily Jacobs, who heads MBP at the University of California, Santa Barbara (UCSB), only 0.5 percent of brain scan studies since 1990 have focused on women’s health. Jacobs and her team are now expanding the project internationally, adding more US institutions and a site in Spain.

Subsequent scans of other mothers have revealed similar patterns of significant volume loss. Interestingly, there seem to be alterations in the brain’s vascular system during pregnancy, particularly involving how cerebrospinal fluid circulates.

“Almost every area of the brain shows substantial changes as pregnancy progresses,” Jacobs shared with ScienceAlert. “We know that the cardiovascular system adapts significantly during pregnancy to support a developing fetus, and we’re seeing that the cerebrovascular system adapts strikingly as well.”

While the findings haven’t yet appeared in a peer-reviewed journal, Jacobs notes that of the 400 brain regions analyzed, 97 percent exhibited changes throughout pregnancy and even after childbirth.

A decrease in overall brain volume might sound alarming. Yet, these changes likely indicate how the brain reshapes itself to optimize functioning for motherhood. After all, this adaptable organ has to manage a limited amount of tissue while navigating substantial life transitions like puberty, pregnancy, or menopause.

“The project and others like it are transforming the way we think about matrescence,” Jacobs noted, “by challenging outdated stereotypes of ‘mommy brain’ as inferior, and instead highlighting the maternal brain’s capacity for continual adaptation and plasticity.”

PhD student Hannah Grotzinger has taken the lead in ongoing data collection for the Maternal Brain Project. The study now involves 20 participants in the US, including both first-time and second-time mothers, along with comparison groups of fathers and non-pregnant women.

These participants are closely monitored over a span of 18 months, using MRI scans, blood tests, and assessments of mood and health.

So far, more than 150 scans have been completed, and the findings among first-time mothers show remarkably similar structural changes.

Brain volume appears to decline steadily during pregnancy, showing some recovery once the child is born. “We are observing widely consistent patterns of remodeling throughout the brain,” explained Jones.

“Overall brain volume, gray matter volume, and cortical thickness decrease significantly during pregnancy and partially rebound postpartum, while cerebrospinal fluid levels show the opposite trend.”

Notably, changes are occurring in the same regions identified in the initial participant, such as the superior temporal lobes and the prefrontal cortex.

The next phase involves growing a larger and more diverse group of mothers to analyze how factors like fertility treatments, pregnancy issues, or breastfeeding influence brain rewiring.

The aim is to create the world’s most comprehensive, open-access maternal brain database. Doing so can help explore questions like how these brain changes affect cognition and whether early indicators of postpartum depression can be detected.

Furthermore, what are the long-term impacts of pregnancy-related conditions such as preeclampsia or gestational diabetes on brain health?

Neuroscientists at UCSB are set to lead this research alongside teams at the University of Pennsylvania and a research institute in Spain. In 2023, Jones discussed the significant gender disparities in brain health research in a piece for Nature.

She pointed out, “It’s not that women aren’t represented—about 50 percent of subjects in neuroimaging studies listed on OpenNeuro.org are women. The issue is researchers aren’t prioritizing studies on health factors specific to women.”

The Global Maternal Brain Project seeks to address this gap.