What happens in a mother's brain during a second pregnancy? Scientists at Amsterdam UMC are finding surprising answers that could help women everywhere.
Elseline Hoekzema and her team at the Pregnancy Brain Lab followed 110 women over time, scanning their brains repeatedly. Some were expecting their first child, some their second, and others stayed childless. This let the researchers watch exactly how motherhood reshapes the brain.
"With this, we have shown for the first time that the brain not only changes during the first pregnancy, but also during a second," Hoekzema said. "Each pregnancy leaves a unique mark on the female brain."
The changes during a first pregnancy were biggest in the Default Mode Network, a brain system that handles self-reflection, social thinking, and emotional processing. But a second pregnancy altered different networks entirely. The most noticeable shifts happened in areas that control attention and respond to sensory information.
"It appears that during a second pregnancy, the brain is more strongly altered in networks involved in reacting to sensory cues and in controlling your attention," explained researcher Milou Straathof. "These processes may be beneficial when caring for multiple children."
The study also found connections between these brain changes and how strongly mothers bond with their children. This link was stronger after a first pregnancy. Researchers also discovered that structural changes in the brain's outer layer, called the cortex, were associated with depression during and after pregnancy for both first and second-time mothers. This is the first evidence that pregnancy-related changes in the cortex connect to maternal mental health.
The timing of these mental health connections differed depending on pregnancy history. For first-time mothers, the brain-depression link was strongest after childbirth. For women expecting a second child, the connection showed up earlier, during pregnancy.
"This knowledge can help to better understand and recognize mental health problems in mothers," Hoekzema said. "It is important that we understand how the brain adapts to motherhood."
The findings, published in the journal Nature Communications, reveal just how remarkable the human brain's ability to adapt really is. Though millions of women experience pregnancy each year, scientists are only beginning to understand how it reshapes the brain over the long term. This research could eventually improve care for mothers, including efforts to prevent and treat postpartum depression.