It tends to occur within several days after birth, and goes away on its own in another few days. See if you can find the matching blister on the corresponding body part. They're especially common in very young babies, whose sweat glands are not yet fully functioning. Keep these areas cool and dry by applying small amounts of plain cornstarch first to your hands, then to your baby. When the stump of the umbilical cord finally drops off, usually after a couple of weeks, the skin at the navel may look a bit raw.
Many doctors advise swabbing the area with alcohol several times a day to keep it dry and clean.
The most severe diaper rashes occur when urine mixes with enzymes in the feces, causing skin irritation, says Dr. Paller. Fortunately, these days the gels in most disposable diapers prevent this. If you're using cloth diapers, or your baby is prone to diaper rash, you should coat her bottom with an ointment containing zinc oxide or petrolatum. Laura Flynn McCarthy writes about health for a variety of national magazines. If you do use soap, moisturizers, or other products, make sure they're fragrance-free and have as few ingredients as possible.