Three brain imaging studies were performed to understand whether past and present experience that parents have may be associated with changes in parental brain during the postpartum period. The first study examined whether perceived quality of maternal care in childhood is associated with brain structure and functional responses to salient infant stimuli among human mothers in the first postpartum month. Mothers who reported higher maternal care in childhood showed larger grey matter volumes in the superior and middle frontal gyri, orbital gyrus, superior temporal gyrus and fusiform gyrus. Furthermore, in response to infant cries, these mothers exhibited higher activations in the middle frontal gyrus, superior temporal gyrus, and fusiform gyrus; whereas mothers reporting lower maternal care showed increased hippocampal activations. These findings suggest an association between maternal care in childhood and neurobiological substrates of parenting behavior in human mothers. The second study investigated the associations between breastfeeding, neurological mechanisms of maternal behavior, and maternal sensitivity at 2-4 weeks postpartum and 3-4 months postpartum. At one month postpartum, when listening to their own baby cry, breastfeeding mothers showed greater activation in brain areas related to maternal behaviors (midbrain, thalamus, anterior cingulate, and superior prefrontal cortex) and emotional information processing (insula, fusiform gyrus, superior temporal gyrus) compared to the formula-feeding mothers. At 3 months postpartum, breastfeeding mothers showed greater activation in areas implicated in maternal behavior (ventral tegmental area, and thalamus), while formula-feeding mothers exhibited increased activations in superior frontal cortex and superior temporal gyrus. Furthermore, across both groups, greater activations in reward-related circuits were associated with higher sensitivity at 3 months. Maternal brain responses at one month postpartum may predict maternal behaviors at later months postpartum and breastfeeding may further promote sensitive maternal behaviors and thus potential long-term positive outcomes for children. The third study examined changes in grey matter volumes in mothers and fathers from 2-4 weeks postpartum to 12-16 weeks postpartum. The longitudinal study using voxel-based morphemetry analysis yielded an increase in the grey matter of prefrontal cortex, parietal lobes, and midbrain for both primiparous and multiparous mothers. Multiparous fathers showed an increase in grey matter particularly in the prefrontal cortex regions whereas primiparous fathers showed little change in brain structure. These results indicate that parenthood over the first three months postpartum is accompanied by structural changes in brain regions important for parental behaviors.