Lanugo is fine, downy hair; it is a type of pelage.
Lanugo grows on fetuses
as a normal part of gestation
, but is usually shed and replaced by vellus hair
at about 40 weeks of gestational age
. As the lanugo is shed from the skin, it is normal for the developing fetus to consume the hair with the fluid, since it drinks from the amniotic fluid
and urinates it back into its environment. Subsequently, the lanugo contributes to the newborn baby's meconium
. The presence of lanugo in newborns is a sign of premature birth
Lanugo is also a common symptom of serious anorexia nervosa
, as the body attempts to insulate itself when body fat is lost. Lanugo may also occur in individuals who are malnourished
due to lack of access to adequate food.
In non-human animals
Lanugo is also common on other animals. For example, seals and elephants are often born with a covering of lanugo.