Lanugo is extremely fine hair that covers your baby's body and, unlike adult hairs on the body, it is not associated with sweat glands. Lanugo hairs begin to be shed now since they are lost into the amniotic fluid in the last few weeks before birth. Your baby then swallows these lanugo hairs in the amniotic fluid but this is not a cause for concern: these hairs provide your baby with an important source of protein, essential to his development. It's been estimated that two-thirds of the protein in the fluid is swallowed and absorbed by the baby's gut each day, providing 15 percent of his protein needs.
The fine lanugo hairs are gradually replaced by vellus hairs, which are short, soft, nonpigmented hairs (often seen more on women and children). Terminal hair is the thicker, coarser, and longer hair that first grows on your baby's eyebrows, then his eyelashes, then his scalp. In adults, facial hair (beards), armpit, and pubic hair, is terminal hair.