Postpartal Neural Plasticity of the Maternal Brain: Early Renormalization of Pregnancy-Related Decreases?

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Human pregnancy goes along with decreasing gray matter volume in the brain of the mother. Whether these reductions remain for years or renormalize shortly after delivery is unclear. The present study used a longitudinal control group design to investigate postpartal neural plasticity. 24 healthy young women were assessed with cognitive and hormonal measures in late pregnancy and underwent a brain scan within the first two months after delivery (TP1). They were compared to 24 naturally cycling women. A follow-up cognitive and imaging measurement was performed three months after the first scan in both groups (TP2, 4-5 months postpartally in the mothers). Compared to the control group, widespread gray matter volume increases from the first to second scan were observed in the new mothers (TP2 > TP1, whole-brain analysis). These were especially pronounced in frontal and cerebellar regions. The time by group interaction pattern of gray matter indicated a postpartal renormalization process, most likely following pregnancy-related decreases. Age was negatively correlated to postpartal gray matter increase in most of the regions. Despite pronounced changes in brain structure, the two groups did not reliably differ in cognitive performance. The results reveal the potential for plasticity in the adult female brain following pregnancy. They support the assumption that the volume reductions during pregnancy renormalize at least partly in the early postpartal phase. The course of renormalization seems to differ between participants of different ages. Future studies are needed to further investigate inter-individual variability and the time course of postpartal neural change.