What Is Pregnancy Brain? The Science Behind Cognitive and Brain Changes During Pregnancy
The term “pregnancy brain” is often used to refer to brain fog, memory deficits, and cognitive impairments affecting 50-80% of people during pregnancy. Pregnancy is experienced by roughly 140 million individuals yearly, yet comprehensive brain studies in this area are only recently being performed. New data shows that cortical shrinkage is observed by nearly 5% is seen throughout pregnancy, however, evidence does not indicate a decrease in brain cells when looking at neural metabolites. The extent of brain changes is often correlated to the levels of estrogen and other related hormones.
Additional key brain areas and functions that are affected by shrinkage during pregnancy include the ventral striatum involved in reward processing, the hypothalamus responsible for instinctive behavior, and the hippocampus which influences memory. Interestingly, similar physiological changes to depression, including decreased hippocampal volume and neurochemical and immune changes are seen during pregnancy. However, the cerebral cortex appears to be the most greatly impacted, which is responsible for information integration throughout the brain. Therefore, the phenomena of “pregnancy brain” and increased risk of mental-health issues may attributed to these neurophysiological changes.
After birth, most neurological changes quickly revert to their levels before pregnancy, with the exception of the default mode network. The default mode network (DMN) is impacted to a degree correlating to the mother and offspring’s attachment, maternal responses, and nesting behaviors. Because the DMN is involved in social processing, theory of mind, and empathy, it is suggested to play a significant role in bonding. Another notable and well-known physiological change post-partum is the plummeting of progesterone levels. Postpartum depression affects about 17% of those who have given birth, most prominently amongst low and middle-income communities, and is likely correlated to progesterone. Although “pregnancy brain” is only one of the major impacts of pregnancy, many of the mechanisms of the physical and mental tolls on the carrier are not well understood leaving minimal treatment or prevention options. As more research is done, additional treatment options, such as zuranolone, the first oral treatment for post-partum depression approved in the U.S. in 2023, may become available.
Source: Drew, L. (2024). How pregnancy transforms the brain to prepare it for parenthood. Nature
