According to a report published in Nature today, pregnancy changes a woman's brain. It alters the size and structure of areas related to perceiving other people's feelings and perspectives, and these changes remain until the baby is a toddler.
These brain changes were directly related to how emotionally attached a mother was to her baby. Experts say that these changes might streamline certain areas of the brain to be more efficient at skills necessary for mothering, including recognizing the needs of her infant, teaching, and nurturing.
The study also scanned the brains of some men before and after fatherhood; they found no difference in brain volume. Researchers say that more study is necessary to understand exactly what is going on here.