Second pregnancy leaves distinct and lasting changes in the maternal brain

Researchers at Amsterdam UMC have discovered that a second pregnancy alters the female brain. Previous research from the same group had already demonstrated the impact of a first pregnancy on the female brain. These results are published today in Nature Communications. The research demonstrates that both a first and a second pregnancy have a strong and unique impact on mothers' brains.

A previous study by Elseline Hoekzema and colleagues was the first to show that pregnancy changes the structure of the human brain. The research group also discovered that pregnancy changes brain functioning. For this follow-up study, they tracked 110 women: some became mothers for the first time, others had their second child, and a third group remained childless. Repeated brain scans allowed them to see exactly what changed in 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. During a first and second pregnancy, the brain changes in both similar and unique ways. Each pregnancy leaves a unique mark on the female brain."

Elseline Hoekzema, head of the Pregnancy Brain Lab at Amsterdam UMC

Different brain networks change

The greatest changes during a first pregnancy occurred in the structure and activity of the so-called Default Mode Network. This part of the brain is important for many functions including self-reflection and social processes. During a second pregnancy, this network changed again, but less strongly. However, during a second pregnancy, there were more changes in brain networks related to directing attention and responding to stimuli. "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", explains researcher Milou Straathof, who analyzed the data. "These processes may be beneficial when caring for multiple children."

Relationship with mother-child bond and maternal mental health

The researchers also found a link between changes in the brain and the bond between mother and child. This link was more prominent during a first pregnancy than during a second. In addition, the researchers observed connections between structural brain changes and peripartum depression, both during a first and a second pregnancy, providing the first evidence that the changes taking place in a woman's cortex during pregnancy relate to maternal depression. For women who became mothers for the first time, this was especially visible after childbirth. For women having their second child, this was particularly the case during their pregnancy. "This knowledge can help to better understand and recognize mental health problems in mothers. It is important that we understand how the brain adapts to motherhood."

Importance of research into the maternal brain

This research provides new insights into how the female brain adapts to motherhood. The large majority of women become pregnant once or multiple times in their lives, yet we are only now starting to unravel how this impacts a woman's brain. This study contributes to addressing this important gap in knowledge on women's biology. The results can also contribute to better care for mothers, for example in preventing and treating postpartum depression. The findings also show that the brain is flexible and can continually adapt to major changes in a woman's life.