When they are born, newborns often have wrinkled skin. They are also coated with a creamy, whitish substance called vernix caseosa. This layer can be localized in certain places or be very extensive. How and why was this “second skin” formed?
In the womb, the vernix caseosa (meaning in Latin “cheese varnish”) protects the fetus from the amniotic fluid in which it bathes. This fatty substance envelops the whole body and makes it waterproof. The vernix caseosa is made up of superficial skin cells, sebum, water, and amniotic fluid debris. It begins to form from around the 20th week of pregnancy and gradually resolves at the end of pregnancy. Its extent is therefore variable depending on the time of the child’s birth: thus, premature babies have a much larger vernix than full-term babies.
Vernix caseosa also plays a role during childbirth, since the lubricated skin facilitates the passage of the baby in the pelvis. It also exerts a protective effect against infections, with also a thermoregulatory function.
Vernix caseosa disappears naturally. It may take a few hours or a few days. In any case, experts are unanimous in recommending delaying the baby’s first bath for at least six hours after birth, or even until the third day. This allows the vernix to fully play its protective role, while enriching the epidermis of the child (massages are also recommended to stimulate the process).