A new study published in Behavioral Neuroscience finds that women's brains may increase in size during new motherhood. The authors took brain scans of 19 moms, 2-4 weeks after birth and again 2-4 months later. They found that these mothers' brains showed growth in midbrain regions, especially those involved with the experience of pleasure and in the prefrontal cortex, which is linked to reasoning, planning and judgement.
New moms who took great pleasure in their newfound role, measured by their use of more positive adjectives to describe their baby (ie. "ideal", "blessed"), saw an even greater growth in the region of the brain that processes emotions.
While researchers aren't exactly sure why these new mommies' brains actually grew, they optimistically simplify things by saying that love has the power to change the brain =)