Varicella in pregnancy, the fetus, and the newborn: problems in management.

As many as 9000 pregnancies annually may be complicated by varicella, which creates management problems for the woman and her fetus or newborn. Estimates on risk to the fetus and to neonates vary widely, making counseling difficult. Likewise, the efficacy of passive immunization of pregnant women or their exposed newborns is not precisely known. In addition to these problems in clinical management, questions remain about the developmental immunology of varicella-zoster virus infection. For example, why do infants exposed in utero to the virus get zoster at an early age and why does passive immunization of newborns appear to be less effective than immunization of older individuals?