What is lanugo?

You’re probably used to seeing longer strands of terminal hair and short strands of vellus hair on your body. But these aren’t the only types of hair common to humans. There’s another type called lanugo.

Lanugo is the hair that covers the body of some newborns. This downy, unpigmented hair is the first type of hair that grows from hair follicles. It can be found everywhere on a baby’s body, except on the palms, lips, and soles of the feet.

Most fetuses develop lanugo around the fourth or fifth month of pregnancy. But the hair is usually not present by the time of birth. It often sheds around the seventh or eighth month of pregnancy, although it can linger and shed weeks after birth. Lanugo at birth is more common in premature babies.

Read more: What is vellus hair? »

Pictures of lanugo

What is the purpose of lanugo?

Throughout the pregnancy, babies grow and develop in a sac filled with amniotic fluid. This protective fluid cushions the baby.

A baby’s skin is covered with a waxy, cheese-like substance called vernix, which protects the skin from amniotic fluid. Vernix prevents a baby’s skin from chaffing in the womb. Lanugo helps protect the skin and makes it easier for vernix to adhere to a baby’s skin.

Why do people with eating disorders develop lanugo?

Once a baby sheds lanugo hair — either in the womb or outside the womb — the hair usually never returns. The only exception is in cases of severe malnutrition.

Because lanugo protects the skin and body, people who are malnourished may grow this hair on their face and body later in life. This occurs in eating disorders such as anorexia nervosa or bulimia. People with anorexia stop eating or eat very little because they fear weight gain. People with bulimia binge eat and then self-induce vomiting to avoid weight gain.

Both conditions can trigger a nutritional deficiency and result in insufficient body fat. Lanugo grows as a physiological or natural response to insulate the body. Eating disorders can disrupt body temperature. When there isn’t enough body fat, the body can’t stay warm.

Does lanugo need to be treated?

Lanugo on a newborn baby doesn’t need to be treated. Even when a lot of hair is present at time of birth, there’s no need to worry. Your baby will naturally shed this hair within the first few days or weeks after birth.

Gently massaging a baby’s skin after birth can facilitate the removal of lanugo. But again, this isn’t necessary. Although massaging can be effective, it isn’t without risks. A baby’s skin is delicate, and if you inadvertently rub your baby’s skin too hard or too much, this can cause soreness, redness, or dryness. Therefore, it may be more beneficial to leave the hair alone and allow it to shed on its own.

In the case of an eating disorder or malnutrition, treating lanugo starts with treating the underlying health condition. An unhealthy body weight can become life-threatening, but help is available. If you have an eating disorder, seek help from your doctor. If you know someone with an eating disorder, encourage them to seek help.

Different treatment options are available depending on the severity of the disorder, such as:

  • inpatient residential or hospital treatment
  • individual counseling
  • support groups
  • nutritional counseling
  • medication (antidepressants, antipsychotics, mood stabilizers)

The takeaway

Lanugo on a baby’s skin isn’t a cause for concern, but if you have questions, don’t be afraid to speak with your doctor. The presence of lanugo on adult skin often points to an eating disorder and shouldn’t be ignored.