Dr. Greene's Answer
It is pretty common for young babies to have soft, thin hair on their faces and backs, called lanugo, that disappears during the first year. It is most common in kids who are born early or who have a darker complexion, but can be seen in any baby.
There is a different type of hair called terminal or adult hair that sometimes shows up in babies. It is coarse and thick, like beard hair. That should be checked by a pediatric dermatologist. In addition, a patch of thick hair on the sacrum (lower back) of a newborn should be checked by a pediatrician.