The cause of cradle cap isn't known. One factor may be hormones that pass from the mother to the baby before birth. These hormones can cause oil glands and hair follicles to make too much oil. This oil is called sebum. Another factor may be a fungus called malassezia (mal-uh-SEE-zhuh) that grows in the sebum along with bacteria. Antifungal treatments often help control symptoms. This supports the idea that malassezia is a cause. An example of an antifungal treatment is ketoconazole. Cradle cap isn't contagious, and it's not caused by poor hygiene.