The plasticity of human maternal brain: longitudinal changes in brain anatomy during the early postpartum period

Abstract

Animal studies suggest that structural changes occur in the maternal brain during the early postpartum period in regions such as the hypothalamus, amygdala, parietal lobe, and prefrontal cortex and such changes are related to the expression of maternal behaviors. In an attempt to explore this in humans, we conducted a prospective longitudinal study to examine gray matter changes using voxel-based morphometry on high resolution magnetic resonance images of mothers' brains at two time points: 2-4 weeks postpartum and 3-4 months postpartum. Comparing gray matter volumes across these two time points, we found increases in gray matter volume of the prefrontal cortex, parietal lobes, and midbrain areas. Increased gray matter volume in the midbrain including the hypothalamus, substantia nigra, and amygdala was associated with maternal positive perception of her baby. These results suggest that the first months of motherhood in humans are accompanied by structural changes in brain regions implicated in maternal motivation and behaviors.

Figure 1

A. Gray matter increase from 2–4 weeks to 3–4 months postpartum, p < .05, (FDR corrected) > 100 voxels—surface areas shown in red—please see Table 1 for complete list of structures that increased in density over time; B. A cluster of midbrain regions are circled in yellow (x = 1, y = −10, z = −15; p < .05, corrected; the vertical color bar indicates t statistical values for the paired t test.), for which gray matter increase from 2–4 weeks postpartum to 3–4 months postpartum was predicted by mothers’ positive perception of own baby at 2–4 weeks postpartum, controlling for parenting experience and scan intervals, β = .44, p = .01.