(HealthDay News) -- Small moles, medically called nevi, appear at birth in about one of every 100 newborns.
They usually don't cause problems, but can rarely develop into a melanoma, a type of deadly skin cancer, the American Academy of Pediatrics says.
So while you don't have to worry about the moles right away, it's a good idea to watch them carefully and have them checked regularly by your child's pediatrician.
A much more serious type of nevus is three inches or larger. It might be flat or raised, and may have hair growing from it. While very rare, occurring in about one of every 20,000 births, it is much more likely than a smaller birthmark to develop into a melanoma, the academy says.