[Risk of chickenpox during pregnancy and the neonatal period].

A newborn fell ill from congenital chickenpox eight days after delivery, a chickenpox rash having been noted in the mother two days before delivery. Administration of zoster-hyperimmune serum to the mother at the onset of the rash and to the child immediately after birth had no demonstrable effect on the course of the disease. Autopsy, the baby having died on the eleventh day post-partum, revealed focal necrotizing pneumonia of all the lobes. Varicella-zoster virus was isolated from lung material. On the basis of present knowledge the risk of varicella infection in the fetus and neonate is 1-7 maternal cases per 10 000 pregnancies. Transplacental passage of the virus can occur at any time during pregnancy. A congenital varicella syndrome is very rare in the first two thirds of pregnancy, but bland infection of the fetus is also likely. Illness of the mother at the end of pregnancy leads to clinically manifest varicella in about a quarter of neonates. The death-rate of congenital varicella is up to 30% if the mother falls ill between the fourth day before and the second day after delivery. Neonatal varicella acquired post-partum takes a relatively mild course. The most important prophylactic measure, in addition to the administration of zoster-hyperimmune serum to the mother within three days of incubation, is to delay delivery past the critical period.