image: Elevated estrogen during pregnancy acts on estrogen receptors in GABAergic neurons within the lateral hypothalamus, increasing firing rates along a projection to the hippocampal CA3 region and leading to temporary memory impairment.
Credit: ©Science Bulletin
Many women report similar experiences during pregnancy: walking into a room and forgetting why, misplacing keys, or struggling to follow conversations. This phenomenon is commonly known as “pregnancy brain” or “mom brain”. Despite its prevalence, its biological basis has remained unclear.
A new study published in Science Bulletin reveals that sustained high estrogen levels disrupt a specific neural circuit from the lateral hypothalamus to the hippocampus, causing temporary memory impairment. The research was led by teams from Baylor College of Medicine, the Second Hospital of Shandong University, Qilu Hospital of Shandong University, and Pennington Biomedical Research Center.
The researchers found that high estrogen levels in the blood, such as those during pregnancy or with certain oral contraceptives, alter gene expression in the lateral hypothalamus. Specifically, high estrogen acts on estrogen receptor alpha in GABAergic neurons of this region, suppressing GABA-A receptor signaling and increasing neuronal firing. These hyperactive hypothalamic neurons project directly to the hippocampal CA3 region, a key hub for memory formation. Silencing this pathway protected mice from estrogen-induced memory deficits, confirming its critical role.
These findings help reconcile a long-standing paradox in estrogen research. While low, cyclic estrogen supports cognition through hippocampal pathways, sustained high estrogen recruits this distinct hypothalamic circuit.
The researchers further validated the mechanism in humans, showing that task-specific memory changes in third-trimester pregnant women correlate directly with circulating estrogen levels. The study confirms that “pregnancy brain” is a real, temporary biological process rather than broader cognitive decline, paving the way for targeted clinical counseling and interventions.
About Baylor College of Medicine
Baylor College of Medicine in Houston, Texas, is a health sciences university known for excellence in education, research, and patient care.
About Shandong University Second Hospital
The Second Hospital of Shandong University is a major tertiary hospital and research institution in Jinan, China, dedicated to clinical care and biomedical research.
About Qilu Hospital of Shandong University
Qilu Hospital of Shandong University is a leading clinical and research medical center affiliated with Shandong University in Jinan, China.
About Pennington Biomedical Research Center
Pennington Biomedical Research Center, a campus of Louisiana State University, is a world-renowned center for scientific research into metabolic health, clinical nutrition, and preventive medicine.