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Lanugo (Newborn Baby Body Hair)

Medically Reviewed by Dr. Pierrette Mimi Poinsett, MD
Updated
Learn about the causes and treatments of newborn body hair.

When we think of hair, our immediate thought is the usual strands we have on our head. But there’s another type that’s generally only seen on newborn babies — officially known as lanugo.

In this article, we’ll discuss what lanugo is, what causes it, and whether it can grow back later in life.


What Is Lanugo?

Lanugo is fine unpigmented hair that begins to grow on the baby from the fourth or fifth month of pregnancy (1).

It’s the first hair that grows from the follicles. It grows everywhere on your baby, except for the palms, lips, and soles of the feet.

Premature babies tend to have more lanugo when they’re born. Although some full-term babies still have some left by the time they’re born, most actually shed this hair inside the womb before the eighth month.

The lanugo begins to grow on the scalp, where it spreads down the face, around the eyebrows, nose, and forehead. It then continues down the baby’s body, until it reaches the feet.

When it begins to shed inside the uterus, the hair incorporates into the amniotic fluid.

Do you know that first dark green squirt of poop our lovely newborn greets us with, called meconium? Yeah, we have lanugo to thank for that. When it dissolves in the amniotic fluid, this is swallowed by the baby, who later disperses of it in their diaper.

When the lanugo sheds, two types of hair replace it: vellus (fine hair) and terminal (thick hair). Terminal hair is what we have on our scalp, arms, and legs.

What’s the Purpose of Lanugo?

Lanugo

Lanugo serves a great purpose inside the uterus. It helps the cheese-like substance, called vernix, to adhere to the baby’s skin by acting as a physical anchor.

This, in turn, helps the vernix fulfill its purpose of keeping the baby’s skin protected from the amniotic fluid.

Another amazing fact is that the lanugo actually helps to increase the baby’s growth rate around mid-gestation. But then toward the end, it decreases the rate of growth (2).

The lanugo hairs send vibrations through the vernix every time your baby moves. When these reach the amniotic fluid, they activate sensory receptors that connect to the nerve endings. These will ultimately end up stimulating your baby’s growth.

Once it gets closer to the last month, the lanugo hair sheds. The stimulation will stop, and the growth rate slows down.

How Long Does Lanugo Remain After Birth?

Only about 30 percent of babies still have lanugo when they’re born. This is no big deal. You may not even notice it straight away since it hides under the vernix.

If lanugo is still present, don’t worry. The hair generally falls outs during the first few weeks. Although, some babies may keep it for as long as a few months!

There is conflicting advice regarding the removal of lanugo if it persists.

Nonetheless, the general advice is to allow the hair to fall naturally. A baby’s skin is sensitive and massage could cause irritation, however gentle the products used may be. If you’re concerned that it’s taking too long, contact your pediatrician for advice.

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Can Lanugo Regrow Later in Life?

Lanugo hair can occasionally regrow in older children or adults. However, this is a bigger mystery and might be a sign of a more serious health issue.

When lanugo regrows on adults, it’s often confused with the thin vellus hair. However, one way to check this is by examining the overall health of the person, as well as the location of the hair. If it grows in new places, for example, the face or hands, it’s likely to be lanugo.

A Patch of Hair Near the Spine

Some mothers may notice that their newborn has a patch of hair near the spine, on the lower back. This is not lanugo hair and is caused by something completely different.

1. Spina Bifida

Spina bifida is a congenital disability that affects the spine. It occurs when the baby’s backbone doesn’t develop properly. This may lead to a damaged spinal cord and nearby nerves, causing different disabilities.

The name spina bifida means “open” or “split” spine since sometimes this condition can cause an opening in the back.

In severe cases, the spine will be visible from the outside, and the child will need surgery to correct it. However, in milder cases, there is no opening, and the defect is hidden (3).

This condition takes place during the first month of pregnancy as the baby’s spine and the nearby nerves develop.

The severity of this condition varies greatly. Mild versions of this defect may only cause minor problems if any at all. However, severe cases can lead to weakness, loss of bladder control, or even paralysis.

2. Spina Bifida Occulta

Children born with a mild version, called spina bifida occulta, may sometimes have it without even knowing. In Latin, “occulta” means hidden, and it basically means that the defect sits under the skin.

However, this type does leave one clue on the lower part of the spine. Sometimes it’s a birthmark or a dimple, or a patch of hair. An ultrasound of the spine can diagnose this condition.

When looking from the inside, the spinal cord is likely attached to the tissue as opposed to being afloat in the spinal column. This may or may not cause any issues for the baby. Fortunately, most babies with this condition won’t experience any long-term problems.

3. Causes of Spina Bifida

Spina bifida generally occurs when your body doesn’t have enough folic acid during the first month of pregnancy. Folic acid is vital for tissue formation, cell growth, and development.

Low levels of this vitamin, both before pregnancy and in the early weeks, will increase the risk of spina bifida, and other neural tube defects.

Sometimes it still occurs, even though the mother has a sufficient amount of the vitamin, although this is rare. In these cases, doctors suspect it could be a genetic defect.

If the mother ran a high fever during her pregnancy or took the drug valproic acid for epilepsy, there’s also an increased risk.


Headshot of Dr. Pierrette Mimi Poinsett, MD

Medically Reviewed by

Dr. Pierrette Mimi Poinsett, MD

Dr. Pierrette Mimi Poinsett is a veteran board-certified pediatrician with three decades of experience, including 19 years of direct patient clinical care. She currently serves as a medical consultant, where she works with multiple projects and clients in the area of pediatrics, with an emphasis on children and adolescents with special needs.

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