Question

What is the name of the fine, downy hair that sometimes covers the back, shoulder, and forehead of a newborn?

Answer 1

Lanugo is the very thin, soft, usually unpigmented, downy hair that is usually found on the body of a fetal or new-born human. The first hair to be produced by the fetal hair follicles is usually seen around sixteen weeks of gestation. It is abundant by the twentieth week.

Complete answer:
Inside the womb, hair grows out of the fetal hair follicles on the fetus's body during gestation. Lanugo helps to anchor the vernix caseosa onto the skin of the fetus to protect it from damage by the amniotic fluid. Vernix caseosa provides lubrication for birth and assists in thermoregulation, prevention of water loss and innate immunity. Without lanugo to anchor vernix onto the skin, these functions would have been compromised. Lanugo is usually shed before normal birth. Even if it's present during birth, it is shed within a few weeks. Lanugo will be found in premature babies but it doesn't mean babies with lanugo are premature.

Note:
Malnutrition also leads to the development of lanugo as a protective response of the body towards the lack of nutrients in its system. Similarly, bulimia patients also exhibit lanugo. It is also found in teratomas (congenital tumours).