White matter microstructure, a measure of the brain’s wiring, peaked at the end of the second trimester. Photograph: Daniela Cossio
Profound Reorganisation Captured From Pre-Conception to Two Years Post-Birth
For the first time, researchers have captured the profound changes that sweep through a woman’s brain during pregnancy, thanks to precision MRI scans taken throughout the process. These scans, conducted from before conception until two years after childbirth, revealed extensive reorganisation in the brain, with some changes fading quickly and others persisting for years.
This groundbreaking study offers unprecedented insight into the maternal brain and sets the stage for deeper research into pregnancy’s neurological effects. The findings could help scientists better understand conditions such as postnatal depression, the link between pre-eclampsia and dementia, and why pregnancy seems to reduce migraines and multiple sclerosis symptoms.
Researchers scanned the brain of a healthy 38-year-old woman who conceived through IVF, collecting 26 MRI images alongside regular blood samples to track hormone fluctuations during pregnancy. The study showed a steady decline in grey matter—the outer layer of the brain—throughout pregnancy, and a temporary spike in brain connectivity near the end of the second trimester.
“The maternal brain undergoes choreographed changes during gestation, and we’re finally able to observe this in real time,” said Prof Emily Jacobs, one of the researchers from the University of California, Santa Barbara.
Earlier studies provided only snapshots of the brain at various stages of pregnancy, often missing transient changes. This new research, published in Nature Neuroscience, fills that gap by capturing changes that might revert to normal by the time of delivery.
Hormones Reshape the Brain
Led by researcher Laura Pritschet, the study showed how the surging hormones of pregnancy—such as estrogen and progesterone—drive widespread physiological and neurological changes. These hormones alter blood plasma, metabolism, oxygen consumption, and immunity, and also lead to significant changes in the brain.
The subject of the study, Dr. Elizabeth Chrastil of the University of California, Irvine, underwent precision MRIs before conception, during pregnancy, and for two years after the birth of her son in May 2020. Despite the intensity of the process, Chrastil noted she didn’t feel dramatically different during pregnancy, saying she didn’t experience the "mummy brain" often reported by others.
The scans revealed a variety of changes: a reduction in grey matter volume, especially in areas linked to social cognition, and increased white matter microstructure—indicating heightened neural connectivity—before it dropped again after the second trimester. Increases in cerebrospinal fluid and brain ventricle size were also observed. These changes appeared closely tied to hormone levels.
“Some people are concerned when they hear about grey matter loss during pregnancy,” Jacobs said. “But it’s likely a reflection of fine-tuning neural circuits, much like the thinning of the cortex that happens during puberty.”
Raising New Questions
The study does not fully explain the emotions or behaviours commonly associated with pregnancy, as factors like stress and sleep deprivation also play a role. However, some brain changes were still detectable two years after childbirth, suggesting more permanent alterations at the cellular level.
“This paper raises more questions than it answers,” Chrastil said. “We’re really just beginning to scratch the surface.”
The research is part of the Maternal Brain Project, an international initiative to gather similar scans from other pregnant women. Prof Jacobs emphasised the need for more research into the neurobiology of pregnancy, pointing out that women’s health has historically been overlooked in biomedical science.
Gina Rippon, a professor emeritus of cognitive neuroimaging at Aston University, hailed the study as "truly heroic," noting how much previous research had missed. Dr. Ann-Marie de Lange, head of the FemiLab group at Lausanne University Hospital, called the study "fascinating." She added that it could help identify biomarkers for conditions like postpartum depression, a serious issue that often goes untreated.
This study represents a major step forward in understanding how pregnancy reshapes the brain and its lasting effects, opening the door to further research into maternal neuroplasticity.
Originally published by https://www.theguardian.com/
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