Despite the adage "new mommy brain" to describe the foggy feeling many new moms experience, a new study finds that certain areas of the brain actually grow larger after a woman gives birth. These areas play important roles in emotion, reward and maternal behavior, and may enlarge in relation to how much new moms "gush" about their babies.

The current study looked at the brains and maternal behaviors of 19 women who had recently given birth. The participants’ brains were scanned at two times points: two to four weeks and three to four months after they had given birth. Additionally, a researcher interviewed the women in their homes, to get an idea of their feelings and attitudes towards motherhood.

These areas play important roles in emotion, reward and maternal behavior, and may enlarge in relation to how much new moms "gush" about their babies.

One variable was the "positive thoughts on baby" measure, which took into account the number of times the women used words like "perfect" and "special". The "positive thoughts on parenting" measure assessed the mothers’ attitudes towards parenting, by tracking use of words like "content" and "blessed".

The researchers found that areas of the brain devoted to maternal motivation, reward and emotion, sensory integration, and reasoning and judgment increased in size across the two time-points. This trend was especially true in mothers who scored higher on the "positive thoughts on baby" measure (i.e., those who gushed more over their little ones). The authors write that "the mother's positive feelings on her baby may facilitate the increased levels of gray matter volume."

The exact nature of this particular relationship between brain and behavior is still unclear: do the changes in the brain lead to the changes in the behavior, or is it the other way around? Kim and her colleagues suggest that the hormonal changes that new mothers undergo may be responsible for the anatomical changes observed in the study. According to the American Psychological Association press release for the article, studies with adopted children may be a good way to tease out the details of how the relationship works.

The authors also suggest that mothers experiencing postpartum depression may actually show shrinkage in the same areas that were shown to increase in size in the non-depressed, doting mothers studied here. More research will certainly been needed to tease apart these intriguing questions.

The study was led by researchers at Cornell University, and was published in the October issue of Behavioral Neuroscience.