L is for Lanugo

The very soft, almost invisible, hair that sometimes covers newborn babies is called lanugo. Sometimes this hair may be dark or even white.  Lanugo starts to develop in the womb around five months gestation and starts to fall out around eight months.  This hair may completely fall out before the baby is born, or your baby may still be covered in, or have patches of, the thin fuzz.  Lanugo is more common in premature babies who are born before the hair falls out.  This covering of lanugo also helps the protective coating of vernix to stick to and coat your baby in the womb.  As the lanugo sheds in the womb it combines with the amniotic fluid which is swallowed by your baby and creates the substance of their first poop, or meconium. 


Shortly after birth or just before birth the lanugo is replaced by vellus hair, which is also very fine, but not as dense as lanugo.  Vellus hairs will continue to cover some parts of the body into adulthood while other parts of the body replace the vellus hair with terminal (adult) hair at puberty.  Terminal hair is typically thicker, longer, and more noticeable.  Lanugo and vellus hairs both help to regulate body temperature which is why it covers the entire body of newborn babies.  It is especially important in premature babies who do not have any body fat to help with regulating temperature. 

Lanugo is one of the many appearances you may not be expecting if you have never seen a newborn baby.  These may include a pointy head from molding, puffy eyes or swelling, vernix, peeling skin, stork bites or birthmarks, mottled skin, blueness in hands and feet, crossed eyes, jaundice, and/or milia. Almost all of these initial appearances will go away or fade with time.

Did your baby still have lanugo when he/she was born?

Next I will be writing about the letter M… M is for Meconium.