She's Got Acne!
Newborns often break out in patches of pinhead-size pimples (white dots on a red base), especially on the face, chest, belly, or back. Her skin may be reacting to the maternal hormones that surged through her in the last few weeks of pregnancy and to the change from amniotic fluid to air.
The best solution: Do nothing. "It was so tempting to try to clean them or pop them, but my pediatrician told me just to leave them alone," says Dorothy Symister of Bronx, New York, whose daughter, Zinzi, is now 2 1/2 months old. It'll clear up within weeks or, at most, a month or two; creams or ointments will just irritate the skin.
If you discover red lesions on your baby's bottom, though, it's a form of diaper rash. To treat it, change her diapers more frequently and let your infant "air-dry" without a diaper for ten minutes or so between changes.
Call the pediatrician if: the pimples are bigger than a pinhead or if they blister, pus, or crust over; she could have a bacterial or fungal infection that requires medication.