New study explains why pregnancy causes memory loss

Scientists have found a biological reason for pregnancy forgetfulness, often called momnesia or baby brain. High levels of oestrogen during pregnancy disrupt a specific brain circuit and impair memory. Researchers ran experiments on laboratory mice to mimic the high oestrogen levels seen during pregnancy. The tests showed temporary memory loss in the animals without any mood changes. The high hormone levels affected a pathway between two brain structures, the hypothalamus and the hippocampus. Oestrogen increased the activity of hypothalamus neurons, which suppressed activity in the hippocampus and led to memory issues.

Human Study and Details

About eighty percent of pregnant women notice these cognitive changes, though this figure comes from self-reports rather than objective tests. Dr. Zheng Sun, a professor of medicine at Baylor College of Medicine, noted that the condition is not serious or medically disabling, but it affects daily functioning and confidence. Typical signs include forgetting why you entered a room, losing the thread of a conversation, or misplacing items. Dr. Yanlin He, director of the Brain Glycemic and Metabolism Control Laboratory at Louisiana State University's Pennington Biomedical Research Center, stated that pregnancy does not make someone less intelligent, as the effects are subtle and specific to certain tasks. The researchers also tested seventy women across different pregnancy stages and found that higher oestrogen levels matched poorer performance on memory tests. When researchers turned off the specific pathway in mice, the memory problems stopped.