We know a lot about the links between a pregnant mother’s health, behavior, and moods and her baby’s cognitive and psychological development once it is born. But how does pregnancy change a mother’s brain? “Pregnancy is a critical period for central nervous system development in mothers,” says psychologist Laura M. Glynn of Chapman University. “Yet we know virtually nothing about it.” Glynn and her colleague Curt A. Sandman, of University of the California Irvine, are doing something about that. Their review of the literature in Current Directions in Psychological Science, a journal published by the Association for Psychological Science, discusses the theories and findings that are starting to fill what Glynn calls “a significant gap in our understanding of this critical stage of most women’s lives.”