Varicella occurs in 0.7 to 0.13% of pregnant women. The risk of transmission of the varicella-zoster virus to the fetus is small. The virus causes malformations (cutaneous scars and above all central nervous system anomalies). Mother-to-offspring transmission is more common during the perinatal period (20%), when mild or severe (fatal in 20% of cases) congenital varicella may occur. Prevention of transmission of the varicella-zoster virus from the mother to her fetus or neonate rests on detection of fetal varicella (antenatal ultrasonography, fetal IgM assays) and on administration of both specific anti-VZ virus immune globulins and acyclovir to the mother and neonate during the perinatal period.