Researchers from the Amsterdam University Medical Center have discovered that a woman's brain undergoes distinct structural and functional changes during a second pregnancy, building upon the alterations from a first pregnancy rather than repeating them. The findings come from the BeMother project, which scanned the brains of hundreds of women, including 127 pregnant women—some expecting their first child and some their second.
The study used multiple MRI scans conducted before conception, during pregnancy, and six months postpartum to track brain changes over time. The results showed that during a first pregnancy, grey matter—the information-processing tissue of the brain—decreases by an average of nearly 5 percent, primarily in the default mode network responsible for daydreaming, memory recall, future planning, and self-reflection.
Grey matter loss is not damage, but pruning
This reduction does not indicate brain damage or reduced intelligence. Instead, experts view it as a form of 'synaptic pruning,' where lesser-used connections are removed to strengthen essential ones, making the brain more efficient for motherhood. Prof Susana Carmona, a co-lead of the study, explained to the BBC: 'I like to use the metaphor of pruning a tree. Some of the branches are cut to make it grow more efficiently. We find in biology, as in life, sometimes less is more.'
Approximately 3.4 percent of the lost grey matter is regained six months after birth, but not all returns fully. The key finding, however, is that changes during a second pregnancy are not simply repeated; they build upon the first. Regions altered the first time show only modest differences the second time, indicating the groundwork for motherhood has already been laid and simply needs fine-tuning for a second child.
Second pregnancy fine-tunes attention networks
Further adaptations occur in networks responsible for attention and responsiveness, likely due to the additional focus needed to care for multiple children. The researchers noted that a second pregnancy 'uniquely changes' a woman's brain, with the timing of changes differing from a first pregnancy. For first-time mothers, changes are more obvious after giving birth, while for women having a second child, changes are more apparent during pregnancy.
The study also suggests a link between brain changes and bonding with a child; those who experienced greater changes were more likely to report bonding well with their babies. Despite these insights, Carmona emphasized that much more work is needed to build a detailed neurological map of the pregnant brain and understand how it transforms as a woman becomes a mother. She hopes further research will improve understanding of pregnancy-related brain changes and ultimately reveal more about mental health conditions such as postpartum depression.
