At what stage does lanugo typically disappear in infants?

Lanugo is a fine, downy hair that covers the body of a fetus, typically appearing around the 20th week of gestation. It plays a role in regulating body temperature and providing some protection to the skin in utero. After birth, lanugo usually begins to shed as the infant transitions to life outside the womb.

The correct answer indicates that lanugo typically disappears within the first few days after birth. This is due to the fact that once the baby is born, the environment changes significantly, and the need for lanugo diminishes rapidly. The body naturally sheds this hair, making way for the development of more permanent hair.

In contrast, the other choices suggest timings that are either too early or too late based on typical developmental patterns observed in infants. For example, lanugo does not generally disappear within hours of birth, nor does it take as long as several weeks or months; the shedding process happens quickly in the initial days following delivery. Understanding this timeline is important for parents and caregivers in recognizing normal infant development.