“Cradle Cap” is a name many Americans give to the condition that causes flaking and scaling on a baby’s scalp and eyebrows in the first few months of life.
Australians call cradle cap “pityriasis capitis.”
When it also involves redness on ears, armpits, neck folds and the groin area, it tends to be referred to as “seborrheic dermatitis” or “seborrhea.”
An Australian Study (Foley, Zuo, Plunkett, Merlin, & Marks, 2003) looked at how often these conditions occurred in the population. Of 1,634 children from ages 11 days to 6 years old, 42% had pityriasis capitis (cradle cap) and 10% had seborrheic dermatitis.
In this study, the amount of children that had pityriasis capitis that were less than 1 year old was 36%.
In the United States there are around 4 million births per year, and 36% of kids in their 1st year of life get cradle cap or pityriasis capitis. So 1.4 million kids each year will get scaling and crusting of their scalp.
In addition to the visual appearance some people find the smell of cradle cap disagreeable.
In summary, 1 in 3 kids in their first year of life will get some degree of flaking, redness, scaling, and scalp irritation from seborrheic dermatitis.
Foley,P., Zuo,Y., Plunkett,A., Merlin, K., & Marks, R. (2003). The Frequency of Common Skin Conditions in Preschool-aged Children in Australia: Seborrheic Dermatitis and Pityriasis Capitis (Cradle Cap). Arch Dermatol. 139(3), 318-322.