Bowling was right not to worry. Baby acne — or newborn acne, as it’s called to distinguish it from infantile acne, which occurs in older babies — is usually harmless and quite common. “It occurs in about 20 percent of newborns, typically around the time when they’re 3 – to 4-weeks-old,” says Mary Yurko, M.D., PhD, a pediatric dermatologist in Grand Rapids, Michigan.
Genetics is thought to be the primary cause of acne in 80% of cases. The role of diet and cigarette smoking is unclear, and neither cleanliness nor exposure to sunlight appear to play a part. In both sexes, hormones called androgens appear to be part of the underlying mechanism, by causing increased production of sebum. Another frequent factor is excessive growth of the bacterium Cutibacterium acnes, which is normally present on the skin.