What is infantile seborrheic dermatitis (cradle cap)?
First of all, cradle cap is a common skin condition in babies, so parents don't need to worry too much! In fact, about two-thirds of babies¹ will develop cradle cap. Cradle cap usually appears in the first few weeks after birth and can last from a few days to a few months, mostly disappearing naturally around the age of two, although it can sometimes last longer.
Is it related to "milk"?
Absolutely not! So unless advised by a doctor, there's no need to change your baby's diet. "Cradle Cap" is called "croûtes de lait" in French, meaning "milk crust," a name derived from its resemblance to dried milk residue that has spilled onto the side of a pot.
Cradle cap looks like dried milk and is easy to identify: it appears as small yellow or brown patches that feel oily and rough to the touch. It most often appears on a baby's scalp and sometimes extends to the eyebrows. In rare cases, it may appear in areas such as the armpits or buttocks.
A few days later, the cradle cap will dry and form a flaky rash (also known as scaling), which will fall off naturally. Will your baby lose some hair during this process? This is normal, but the hair will grow back, so there's no need to worry.
Although cradle cap may not look very nice, it is only a surface condition and will not cause pain; at most, it will only cause the baby slight discomfort.
How does cradle cap form?
Is cradle cap caused by insufficient cleaning? Not at all! Cradle cap is somewhat similar to adult dandruff; it's less of a cleaning issue and more of a natural skin reaction. This further proves that cradle cap is not a serious problem.
Specifically, cradle cap is caused by excessive sebum secretion from a baby's skin. Overactive sebaceous glands produce too much sebum to protect the skin, leading to oily areas where dead skin cells accumulate. These trapped cells form small scabs, mainly on the scalp.
So, why are a baby's sebaceous glands so active? The answer is hormones during pregnancy! Mothers may think they're out of hormonal influence, but the baby may still have some of their mother's hormones remaining in their system. Once these hormones are completely metabolized, the cradle cap will disappear.
During this period, excessive sebum production can also promote the growth of a common skin yeast called Malassezia Furfur. This yeast proliferation can trigger a reaction in the baby's skin, further contributing to the formation of cradle cap.
In summary, maternal hormones in a baby's body stimulate excessive secretion of sebaceous glands, which in turn promotes the growth of Malassezia. These two factors together create ideal conditions for the formation of cradle cap, which is especially likely to appear on a baby's scalp.
Source: (1) C Moises-Alfaro et al, In J Dermatol 2002, 41, 349-351.
