Lanugo

Overview

What is lanugo?

Lanugo is soft, fine hair covering a fetus while inside the uterus (womb). It helps protect them and keeps them warm while they grow. Some newborns have lanugo covering their bodies at birth, especially if they’re born prematurely. Lanugo can develop in people with eating disorders or certain tumors.

Who gets lanugo?

Lanugo is most common in unborn babies or newborns. However, people with eating disorders or certain tumors or cancers can grow lanugo.

Fetal development

Unborn babies develop lanugo between 16 to 20 weeks gestation. It covers their entire body except for places without hair follicles. Areas without hair follicles include their lips, palms, nails, genitals and soles of the feet. Your baby typically sheds lanugo before birth, but some newborns still have it at birth. Premature babies are more likely to have lanugo than babies born at full term (39 weeks). If your baby is born with lanugo, it should disappear on its own.

People with anorexia or bulimia

Children or adults with an eating disorder can develop lanugo hair. Experts believe this may happen because their body has difficulty keeping warm. It may be a sign that the person is extremely malnourished.

Certain types of tumors

Some people with teratoma develop lanugo hair. Teratoma is a rare type of germ cell tumor. There have been a few cases of someone developing lanugo due to cancer.

Function

What does lanugo do?

Lanugo is an essential part of fetal development. It’s your baby’s first hair, and it plays a critical role in protecting their skin and keeping them warm in the womb.

Lanugo helps vernix (the waxy, cheese-like substance that covers the fetus) stick to the skin. Vernix helps protect a fetus’s body from amniotic fluid inside the womb. Amniotic fluid could damage their delicate skin without lanugo and vernix. When vernix is held in place by lanugo, it helps insulate the body and protect the skin. Lanugo also helps your baby stay warm and regulates their temperature until they develop enough body fat to serve this purpose.

Lanugo also helps your baby grow. This occurs because the lanugo hair sends vibrations to your baby’s sensory receptors when it moves. These receptors stimulate your baby’s growth. When lanugo falls off, the stimulation stops, and your baby’s growth slows down. Experts are not entirely sure how this happens, but continue to study this and other hormonal effects of lanugo.

When does lanugo fall off?

Most unborn babies shed lanugo shortly before birth. About 30% of all full-term babies are born with some lanugo. If your baby is born premature (before 37 weeks), they have a greater chance of having lanugo. It may take several weeks to go away, but lanugo will fall off on its own.

Lanugo typically falls off in the last eight weeks of pregnancy. Once it’s shed from the skin, it mixes in with amniotic fluid. Because your baby swallows amniotic fluid in the uterus, lanugo becomes part of your baby’s first food. Your baby will pass the tiny hairs in their first poop at birth, called meconium.

After your baby sheds lanugo, they develop vellus hair, a fine, peach-fuzz-like hair. The vellus hair continues to help regulate temperature until adult hair (terminal hair) grows in.

Why do people with eating disorders get lanugo?

Lanugo is one of the side effects of anorexia nervosa, bulimia nervosa and other eating disorders in adults. It can indicate poor nutrition and malnourishment. Healthcare providers believe lanugo grows when a person doesn’t have enough body fat to keep them warm. In response, their body grows lanugo to help insulate the body.

Anatomy

What does lanugo look like?

Lanugo hair is soft, thin and feathery. If your baby is born with lanugo hair, they may look like they're coated in a layer of delicate fur. Lanugo can grow everywhere except the palms, lips, genitals, nails and soles of the feet. It’s easiest to see lanugo on your baby’s back, shoulders or tailbone, but it can grow anywhere there is a hair follicle.

What color is lanugo hair?

Lanugo hair can range in color from very light to dark. Your baby’s genetics play a role in how light or dark the hair may be. For example, if your baby has darker skin, lanugo may be more visible than in a baby with fair skin.

What happens to a baby’s lanugo hair?

Your baby sheds its lanugo hair sometime in the seventh or eighth month of pregnancy. In this case, the lanugo mixes with amniotic fluid and gets swallowed by your baby. However, some babies are born with lanugo, especially if they are born before 37 weeks gestation (premature). If your baby is born with lanugo hair, it will go away on its own over time.

Conditions and Disorders

When is growing lanugo a sign of a medical condition?

Lanugo isn’t a cause for worry when it’s seen in newborns. However, severe eating disorders or malnutrition can cause lanugo. In rare cases, it’s been linked to tumors or cancer. If you’re an adult and notice lanugo on your skin or on the skin of a friend, it’s a good idea to talk to a healthcare provider.

Is it bad for a baby to be born with lanugo?

No, it’s not bad for a newborn to have lanugo. If your baby was born premature, it’s normal to have lanugo hair on the skin. Full-term babies are less likely to have lanugo at birth, but it’s possible. Lanugo should fall off within a few weeks.

How do you treat lanugo on an adult?

Treating lanugo in adults involves treating the underlying condition. In the case of anorexia, bulimia or other eating disorder, getting help to treat these conditions is the first step. Lanugo develops as a defense mechanism in people who are underweight to maintain body temperature.

If a tumor causes lanugo, your healthcare provider will typically remove the tumor. Even if the tumor isn’t cancerous, it can rupture or lead to other problems. If your tumor is cancerous, your healthcare provider may recommend chemotherapy, radiation therapy or a combination of the two in addition to surgical removal. Once the tumor is treated, the lanugo hair should stop growing.

Care

When will lanugo hair go away on newborns?

Lanugo disappears within the first two months of life. However, babies may still have fine, peach-fuzz-like hair on the tops of the ears, above their tailbone or at the base of their neck. This is normal and shouldn’t be a cause for concern. If you have any questions about the hair on your baby’s body, talk to your child’s pediatrician.

Should you remove lanugo hair?

No, you shouldn’t wax, shave or remove lanugo hair from your baby. This will irritate your baby’s highly sensitive skin. If you're an adult with lanugo, shaving or waxing may be an option. However, it will continue to grow back until the underlying condition is treated.

A note from Cleveland Clinic

Don’t be alarmed if your baby is born with lanugo. This soft, fine body hair should go away soon. Talk to your baby’s pediatrician if you have questions or if it doesn’t go away on its own. Lanugo on adults can indicate an eating disorder or other serious health condition. If you notice lanugo on a child, teen or adult, encourage them to talk to their healthcare provider as soon as possible.

Last reviewed by a Cleveland Clinic medical professional on 03/11/2022.

References

  • American Pregnancy Association. Second Trimester: Fetal Development. (https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/second-trimester/) Accessed 3/11/2022.
  • KidsHealth. The First Day of Life. (https://www.kidshealth.org/en/parents/first-day.html) Accessed 3/11/2022.
  • Strumia R. Skin signs in anorexia nervosa. Dermatoendocrinol. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2836432/) 2009;1(5):268-270. doi:10.4161/derm.1.5.10193. Accessed 3/11/2022.
  • Verhave BL, Nassereddin A, Lappin SL. Embryology, Lanugo. (https://www.ncbi.nlm.nih.gov/books/NBK526092/) [Updated 2021 Oct 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 3/11/2022.

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