When we think of new babies, we tend to think of perfectly pink, clean bundles of love. So it may be surprising when your baby is born with white goo all over his body. What is that stuff?! Well, that’s vernix caseosa (more commonly referred to as vernix) and it literally means “cheesy varnish.” This white, cheesy coating protects your baby in the womb, during delivery, and after birth, and it’s really pretty amazing.

Vernix begins to form during the twentieth week of gestation. Maternal hormones and sebaceous lipids signal the sebaceous glands to begin excreting this substance.

What is vernix made of?

One of the main functions of vernix is to protect the baby’s skin from the amniotic fluid (so it does not become “waterlogged” during gestation), so it is rather ironic that its composition is roughly 80% water. It is also composed of lipids (fats), amino acids, proteins, and antibacterial and antimicrobial compounds. 60% of what makes up vernix is not found anywhere else! How incredible is that? Scientists have yet to replicate vernix for protective use in infants born before 27 weeks (it is scarce at this time but can be beneficial).

What does it do?

Because vernix has SO many function, the most logical way to explain what it does is to break it down into three parts: during pregnancy, during delivery, and after birth.

During Pregnancy

• The main function during pregnancy is to protect the baby’s skin from amniotic fluid (think about how your skin would look if it was in liquid for 40 weeks). Because of the antimicrobial and antibacterial properties of vernix, it also protects baby from meconium should they pass any prior to delivery.
• It also helps prepare baby for life after delivery. Towards the end of pregnancy, the vernix thins and is shed into the amniotic fluid, which the baby then ingests. Some of the proteins found in vernix are also present in breast milk. Its ingestion exposes baby’s digestive system to these proteins, preparing baby for nursing.
• Because of the antimicrobial and antibacterial nature of vernix, it also protects baby from unwanted bacteria, most commonly after your water breaks. Baby may be exposed to these unwanted pathogens through vaginal exams or from migration from the vagina (which is why most providers want you to deliver within 24 hours of your water breaking).

During Delivery

• Vernix protects your baby from undesirable bacteria in the birth canal.
  • E. coli
  • Group B Strep
  • Staph aureus
  • Pseudomonas aruginosa
  • Klebsiella pneumonia.
• While protecting baby from potentially harmful bacteria, it also helps baby pick up and hold onto good bacteria. I mean, HOW FREAKING AMAZING IS THAT??
• It acts as a lubricant during delivery to help ease baby’s transition to the world.

After Delivery

• After birth, vernix acts as an insulating layer and can help your baby regulate their body temperature. This is part of the reason why skin-to-skin is more effective than an artificial incubator!
• Vernix smells like amniotic fluid and the two smell like breast milk. Leaving vernix on your baby for the first 24 hours can contribute to breastfeeding success.
• It is a great moisturizer for baby’s skin (and your own).
• As long as your baby has not been washed, the hospital staff must wear gloves when handling your baby. The physical barrier created by the gloves prevent microbe transmission to baby while in the hospital.

How long should we leave it on the baby?

Your baby’s skin absorbs the majority of the vernix on his skin within the first 24 hours of birth. You should delay your baby’s first bath for at least 24 hours in order for them to benefit from this unique substance. However, it is important to note that it is is not fully absorbed until 5-6 days after delivery (once your mature milk has come in), so if possible, it is best to wait at least a week to bathe your baby.

Are all babies born with vernix?

Yes and no. Your baby begins to synthesize vernix around week 20. Because of this, babies born after 20 weeks gestation are born with some vernix, but not as much as babies who are born closer to full term (it is still being synthesized). Babies who are born before 27 weeks and after 40 weeks tend to have less vernix present than babies born between 27 and 40 weeks.

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This article is for informational purposes only. The content does not take the place of  consultation with your healthcare provider.