What Is Vernix Caseosa?

When your baby is born, their skin might be covered with a layer of a white, waxy substance called vernix caseosa. It might be thick or thin and can be patchy or cover them all over, but vernix, as it is commonly called, has several crucial benefits for your little one. Namely, this coating helps protect their skin and offers a bit of lubrication during childbirth. Here's what you need to know about vernix on your newborn.

What Is Vernix?

Humans are the only animals whose newborns are coated in vernix caseosa. The waxy substance comes from the sebaceous glands, which will be responsible for producing skin oils as your little one grows. Vernix caseosa also contains shed skin cells.

Vernix first appears on your baby's skin around the 19th week of gestation. Some of your baby's vernix will dissolve into the amniotic fluid starting after around 34 weeks. For this reason, babies who are born early will typically have more vernix on their skin than full-term babies do. Additionally, it's normal for the amount of vernix remaining on a baby at birth to vary from newborn to newborn—and how much is still on your baby's skin at birth is not a cause for concern.

What Vernix Looks Like

Are you wondering what vernix looks like? It usually has the following characteristics:

• Appearance in patches on your newborn's skin
• Thick, waxy texture
• Creamy white color
• Resemblance to an opaque lotion that wasn't rubbed in

If the vernix has a yellowish-brown or green tinge instead, that's a good indicator that your baby already passed meconium (the first poop) in the womb.

What Vernix Does

In the womb, vernix helps protect your newborn's delicate skin from the acidic quality of the amniotic fluid. It hydrates their skin, insulates their body, and maintains a proper—and comfortable—temperature in utero. Vernix also acts as a lubricant, helping your baby slide out of the birth canal a bit easier, says Laura Riley, M.D., an OB-GYN in New York City.

Research has linked leftover vernix caseosa to the intoxicating "new baby smell" associated with infants. This smell may play a part in triggering sensations of love and pleasure in new parents. What's more, vernix muffles sound for fetuses: Although they can start to hear your voice by about week 25 gestation, their ears are covered with sound-shielding vernix.

Do All Babies Have Vernix?

All babies develop a coating of vernix while in the womb, but the amount of vernix left on their skin at birth varies widely. In fact, if your baby is overdue, the vernix may be scant or missing entirely. The reason: It was likely already absorbed in the amniotic fluid. Babies without vernix might have drier skin than others, but this does not cause any harm to your baby.

How Long Does Vernix Last?

Though vernix can look a little unsightly, don't be so quick to wipe it off your newborn's skin, advises Ari Brown, M.D., a pediatrician in Austin, Texas, and founder of 411 Pediatrics and the author of Expecting 411, Baby 411, and Toddler 411. Research shows that removing vernix is not necessary for hygiene, and leaving it may help stave off bacterial infections and heal wounds. The World Health Organization advises delaying a baby's first bath for at least 6 hours after birth, although 24 hours is ideal.

The exception: Wash vernix off right away if it has meconium staining, or if the birthing parent has HIV or hepatitis.

Once the vernix is washed away, your baby's skin may dry out and peel—mostly on the feet and hands. Leave the flakes alone; they'll usually disappear on their own within a couple of weeks.

Keep in mind that vernix likes to hide in skin folds for several days or even weeks after delivery. If you discover it, you can gently wipe it away or simply leave it until it comes off naturally.