What does the term "lanugo" refer to in neonatology?

Lanugo refers to the fine, soft hair that covers a newborn's body. This hair is typically present during gestation, primarily between the 16th and 20th weeks of pregnancy, and it serves several functions, including helping to anchor the vernix caseosa— a protective substance that coats the skin of the fetus. While it's common for preterm infants to have a significant amount of lanugo, full-term infants may have less or may have already shed most of this hair. Lanugo gradually disappears after birth, usually within a few weeks, as the infant develops more typical body hair.

Understanding lanugo is important in the context of neonatal care, as its presence can provide insight into the gestational age of the newborn and their development in utero.