If a pregnant woman is having chicken pox, does that mean her baby has them too?

Pregnancy and CP: Chickenpox in the first 20 weeks of pregnancy can very occasionally (one to two percent of cases) cause damage to the developing foetus. The types of abnormalities that can occur affect the skin (scarring), the limbs (shortening), the brain (mental retardation) and the eyes (blindness). In addition, chickenpox at any stage of pregnancy is a significant risk to the mother, particularly for chickenp.