This is Your Brain on Parenting Anne Mosle We have learned so much about the powerful brain burst moments in the early years of life and the impact toxic stress, trauma, and poverty have during this critical period for babies. Research shows a baby's brain can double in size by the first year and by the child's fifth birthday, 95 percent of their total brain growth has taken place. What we now know, thanks to the work of Dr. Sarah Watamura, Dr. Pilyoung Kim, Tiffany Phu, and Andrew Erhart from the University of Denver in Two Open Windows: Part II, is that adults transitioning to parenthood are also experiencing brain bursts. In fact, all caregivers, regardless of biological connection to their baby, experience brain developments as they become parents, like learning if a baby’s cry means they are hungry or needs a diaper change. The science now calls us to think Mom Plus and extend proven supports like home visits and stress-reduction classes to fathers, adoptive parents, and other adults who take on the primary parenting responsibilities for a young child.