From around the 20th week of pregnancy, a waxy substance called vernix caseosa, known as vernix develops and coats the unborn baby’s skin.
This waxy coating is made from lipids, proteins and water (forming sebum), and is secreted from the baby’s glands.
Vernix is a natural skin protectant, whilst in utero surrounded by amniotic fluid and also has antimicrobial properties and protects the baby’s skin.
During birth the vernix also assists the baby's passage through the birth canal.
When left on the baby's skin post birth, and not rubbed or washed off, it has been found that a baby's skin is more hydrated, less scaley and undergoes a more rapid decrease in the pH, and helps the baby conserve heat than when the vernix is removed.
Vernix also is the best natural moisturizer ever and helps to keep your baby's skin soft and supple. Amniotic fluid, which bathed the baby before birth has the ability to provide some extra resistance to infection as well, so the longer it remains on the skin, the better for baby.
Babies born post 42 weeks lose the vernix the longer the mother is pregnant, so when babies born at 42 weeks the vernix might not be as visible anymore, usually there is still some hidden in the folds of their skin and under their arms.
Babies born earlier often have a larger amount. Research indicates that vernix has immune properties and leaving it on your baby's skin provides a layer of protection while the new baby's immune system is getting stronger, which is a really beneficial especially for babies who are born in the hospital, with lots of potential for exposure to hospital-acquired infections.
Host defence proteins in vernix caseosa and amniotic fluid.
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