Varicella is an infection perceived to be a benign disease. But if adults get the disease, especially if pregnant mother gets chicken pox, it could be fatal or could cause disease in the unborn baby varying from fetal varicella syndrome to neonatal varicella—both causing significant morbidity and mortality. Understanding of the disease is very important, especially at what age it can cause problems. Unlike many other viral infections, varicella during pregnancy can cause different problems at different gestations.