Introduction
In a quest to understand the intricate changes during pregnancy, a neuroscientist turned her own journey into an extraordinary research project.
When a cognitive neuroscientist decided to start a family, she and her husband embarked on a unique scientific venture. Utilizing in vitro fertilization, she had her brain scanned before, during, and after pregnancy to observe the effects of gestational hormones on brain structure.
The idea came to life when the neuroscientist, referred to as Chrastil, approached Emily Jacobs, a fellow neuroscientist at the University of California, Santa Barbara. Jacobs, whose lab had previously scanned brains during menstrual cycles, enthusiastically supported the project.
While previous studies had compared brain structures before and after pregnancy, this project was the first to monitor the brain continuously throughout the 40 weeks of gestation. Understanding these changes could help clinicians address conditions like postpartum depression, epilepsy, and migraines more effectively.
Profound Changes Observed
Over 26 MRI sessions, starting three weeks before conception and continuing periodically for two years post-birth, Chrastil’s brain revealed significant changes. The grey matter, responsible for emotion, reasoning, and language, shrank. The cortex thinned, and total brain volume decreased. Surprisingly, the white matter, which transmits information between brain cells, strengthened—an unprecedented discovery.
These findings, first published as a preprint on bioRxiv, suggest that pregnancy induces dramatic changes in a woman’s brain and highlight the adult brain's capacity for extensive remodelling. While changes in grey matter and cortical thickness were known to persist post-pregnancy, this study found that white matter changes revert to pre-pregnancy levels.
The Hormonal Symphony
Pregnancy induces a cascade of physiological changes. Blood volume increases by 50%, oxygen consumption rises by about 20%, and hormones such as estrogen and progesterone surge to levels 100 to 1,000 times higher than normal. Researchers believe these changes, observed in animal studies, facilitate maternal behaviours and bond formation between mother and infant.
“Rodent models show striking brain changes at the cellular level, enhancing mothers' sensitivity to their pups' needs,” Jacobs explained. “Human brain remodelling likely serves a similar purpose, improving social cognition and parental attachment.”
Susana Carmona, a senior researcher at the Hospital General Gregorio Marañón in Madrid, has also documented these changes. “The greater the brain changes during pregnancy, the higher a mother scores on maternal attachment tests,” she noted. Researchers are now exploring how these changes in gray matter volume enhance maternal attachment.
Comparing Adolescence and Pregnancy
The brain restructuring during pregnancy mirrors adolescence, another period marked by significant hormonal changes and brain pruning. “Adolescence involves hormonal rises that remodel the brain for behaviours suited to that life stage,” said Laura Pritschet, a postdoctoral fellow at the Perelman School of Medicine and lead author of the study. “Similarly, pregnancy hones neural connections to prepare for parenthood.”
While Chrastil’s study serves as a proof-of-concept, its findings cannot yet be generalized. However, Jacobs and Chrastil aim to recruit more women to establish normative data on pregnancy-induced brain changes.
“Our goal is to build the most comprehensive database on pregnancy,” Jacobs stated. “This research could continue for the next decade, yielding invaluable insights into the maternal brain.”
This groundbreaking study opens new avenues for understanding the profound transformations during pregnancy, providing a deeper appreciation for the intricate interplay between hormones and brain structure.
References
- Jacobs, E., & Chrastil, E. (2023). Longitudinal Mapping of Brain Structure Changes During Pregnancy.bioRxiv. Retrieved from
- Carmona, S., Martínez-García, M., Paternina-Die, M., Barrios, M., Llorente, R., & Martínez-Cengotitabengoa, M. (2017). Pregnancy and the Brain: Maternal Brain Adaptations to Pregnancy and Motherhood.Nature Neuroscience Reviews, 18(11), 761-772. DOI: 1038/nrn.2017.82.
- Kim, P., Leckman, J. F., Mayes, L. C., Newman, M. A., Feldman, R., Swain, J. E. (2010). The Plasticity of Human Maternal Brain: Longitudinal Changes in Brain Anatomy During the Early Postpartum Period.Behavioral Neuroscience, 124(5), 695-700. DOI: 1037/a0020884.
- Pritschet, L., Jacobs, E. G., & Grafton, S. T. (2018). Hormonal Dynamics Associated with Menstrual Cycle Phase and Cognitive Performance.Frontiers in Neuroscience, 12, 281. DOI: 3389/fnins.2018.00281.