What is the term for fetal hair?

The term for fetal hair is "lanugo." This type of hair is fine, soft, and typically appears on the body of a developing fetus during pregnancy, usually between the 16th and 20th weeks of gestation. Lanugo serves a purpose in fetal development; it helps to regulate body temperature and provides a protective layer for the delicate skin of the fetus. It is usually shed before birth, or shortly after, and is replaced by other types of hair.

In contrast, vellus hair refers to the fine, light-colored hair that covers much of the human body after birth. Terminal hair, on the other hand, is the thicker, coarser hair found in certain areas, such as the scalp, beard, and armpits, which typically develops during puberty. Follicular hair is not a standard term used in the classification of hair types. Understanding these distinctions helps clarify why "lanugo" is the correct term for fetal hair.