Birth crowning, which is when your baby's head starts to emerge bit by bit during each contraction, occurs during the second stage of labor. (A contraction is when the uterine muscle tightens and relaxes to help your baby pass from the uterus into the birth canal.) As you push, your baby's head may appear, but after the contraction is over, it will withdraw from view once again.
"Once you can see the head and it doesn't slip back in, that's crowning," says Ami Burns, childbirth educator and doula. "A fun way to think of it is that birth crowning occurs when you can see the part of the head where a princess would wear her crown." Once crowning occurs, your baby's arrival is imminent.