Infants are no strangers to rashes and other skin conditions and irritation, from diaper rash and cradle cap to baby acne and milia. About 40 percent of newborns develop pediatric milia, and it usually appears within the first week after delivery [source: Agrawal].
Pediatric milia and baby acne are often confused with one another, but in truth the conditions not only look dissimilar (they're different colors) they are caused by different things. Baby acne is exactly what you think: red pimples. Baby acne tends to develop about three to four weeks after birth, and it typically affects the face (on the cheeks, the nose and the forehead) [source: MedlinePlus]. While there have been theories why so many newborns develop acne around the one-month milestone, there is currently no known reason for why this skin issue develops.
Pediatric milia, like baby acne, typically appears on the face (on the cheeks, chin and forehead) but instead of red pimples this condition is small white bumps no more than two millimeters in diameter [source: Agrawal]. The condition is completely harmless and happens when dead skin cells get trapped near the surface of the skin instead of flaking off. When the condition happens inside the mouth it's called Epstein's pearls.
Just like baby acne, pediatric milia and Epstein's pearls disappear on their own, without treatment.