A second pregnancy changes the brain in ways that are both familiar and different from a first pregnancy, according to new research from Amsterdam UMC published in Nature Communications. Building on previous work showing that a first pregnancy remodels the brain, the researchers found that each pregnancy leaves its own unique imprint on the maternal brain.
In a previous study, Elseline Hoekzema and her colleagues were the first to show that pregnancy changes the structure of the human brain. They also showed that pregnancy affects brain function. For this latest research, the team followed 110 women over time. Some were expecting their first child, others were pregnant with their second, and others had no children. By performing repeated brain scans, the researchers tracked how the brain changed over the course of the study.
“With this we have shown for the first time that the brain not only changes during the first pregnancy, but also during the second,” says Hoekzema, director of the Pregnancy Brain Laboratory at UMC Amsterdam. “During the first and second pregnancies, the brain changes in similar and unique ways. Each pregnancy leaves a unique mark on the female brain.”
Brain networks change in different ways
The researchers found that the first pregnancy produced the greatest changes in the structure and activity of the brain’s default mode network, a system involved in self-reflection, social thinking, and other important mental functions.
During a second pregnancy, this same network changed again, although to a lesser extent. Instead, the most notable changes occurred in the brain networks responsible for directing attention and responding to sensory information.
“It seems that during a second pregnancy, the brain is most strongly altered in the networks involved in reacting to sensory signals and controlling attention,” explains researcher Milou Straathof, who analyzed the data. “These processes can be beneficial when caring for multiple children.”
Brain changes related to maternal bonding and mental health
The study also discovered a relationship between pregnancy-related brain changes and the emotional bond between mother and child. This connection was stronger after a first pregnancy than after a second.
The researchers also identified links between structural changes in the brain and peripartum depression during the first and second pregnancies. According to the team, this is the first evidence that changes that occur in the cerebral cortex during pregnancy are associated with maternal depression.
The timing of these associations differed by pregnancy history. Among new mothers, they were most evident after giving birth. For women expecting a second child, they were most noticeable during pregnancy.
“This knowledge can help better understand and recognize mental health problems in mothers. It is important that we understand how the brain adapts to motherhood.”
Understanding the maternal brain
The findings offer new insights into the remarkable adaptability of the maternal brain. Although most women experience one or more pregnancies during their lifetime, scientists are just beginning to understand how pregnancy influences the brain in the long term.
Researchers say these discoveries help fill an important gap in knowledge about women’s biology and could eventually improve care for mothers, including efforts to prevent and treat postpartum depression. The study also highlights the brain’s remarkable ability to continually adapt to important life experiences, such as pregnancy and motherhood.