Photo of a newborn's swollen breasts

Before birth, the mother's hormones pass through the baby's system. This can lead to swollen breasts at birth — for both boys and girls.

Newborn girls might have light vaginal discharge and a swollen vulva as well. Vaginal discharge might last only several days, and the swelling typically disappears within two to four weeks.

For some newborn boys, fluid is squeezed into the scrotum during birth. This swelling, known as a hydrocele, usually disappears within a few months. Frequent erections are common, too.