New research shows that new mothers grow bigger brains after giving birth.

Increases in estrogen, oxytocin and prolactin may contribute to brain reshaping in the areas of motivation and behavior, according to findings published in Behavioral Neuroscience.

MRI scans of women’s brains before and after birth showed that women who gave birth had small gray matter increases in certain parts of the brain: areas related to maternal motivation, reward and emotion processing, sensory integration, and reasoning and judgment.

Women who were most enthusiastic about their babies were significantly more likely to develop bigger midbrains.