So we ask the nurse practicioner
after the film
: Why did that newborn
look like a ghost
"Oh, that's just the vernix. It's a cheesy coating you'll often see on premature babies. It's harmless."
A cheesy coating? Now I'm picturing my future child floating in amniotic fluid smearing brie all over its body (the OED cites a journal reference that makes the analogy to cream cheese). And the medical literature does indeed refer to the consistency of the vernix as "cheesy" or "waxy." Vernix: Latin for "varnish." Caseosa: Latin for "cheese."
This greyish-white coating is secreted by the sebaceous glands (of the fetus) around week 20, and coats the fetus to protect the skin from the constant exposure to amniotic fluid. Without it, the skin would wrinkle like a prune. Full term and late newborns will have almost none, except for maybe in the folds of their skin and under their fingernails. The loss of vernix may cause the skin to peel during the first postnatal week.