Pregnancy is no easy business—as your mother has probably pointed out many times (and as you may have reminded your own children). But among the many, often-uncomfortable changes that happen within a woman’s body during pregnancy, there is at least one unexpected plus side: a bigger brain. A team at the National Institute of Mental Health conducted MRI scans of women before and after birth, and found growth of gray matter in the parts of the brain that affect reasoning, judgment and sensory perception. So, remember all those times growing up, when your mom somehow knew what you were up to without having to be told? It wasn’t ESP. It was merely her mutant superpowers at work.