Typically, a baby’s hair will grow in by the time they are 6 months to 12 months old, but when your baby has a full head of hair can vary greatly from 12 months to 2 or 3 years.

A Study Debunking the Myth. A 2017 study in the Journal of Pediatric Dermatology tracked 100 infants split into two groups: one with shaved hair and one without. After 12 months, researchers found ...