First Trimester: Varicella Zoster Virus
Varicella zoster virus (VZV) causes the illnesses known as chickenpox and shingles. Although most pregnant women have already been exposed to the virus and therefore are immune, some may not have had the infection or been immunized. Since the virus can cause birth defects or illness in the baby (depending on when during the pregnancy an infection occurs), testing for VZV is available before or early in pregnancy to determine if the woman has antibodies to VZV.
If a woman is already pregnant, she cannot receive the vaccine for VZV and should avoid being exposed to anyone who has chickenpox or shingles. If it is determined that a pregnant woman may have been exposed to the virus, treatment is available that can prevent or weaken the severity of the illness.