If you are pregnant and have chickenpox (varicella) — a highly contagious viral infection that causes an itchy, blister-like rash — you and your baby might face serious health risks.

If you develop chickenpox during pregnancy, you are at risk of complications such as pneumonia. For your baby, the risks depend on the timing. If chickenpox develops during the first 20 weeks of pregnancy — particularly between weeks eight and 20 — the baby faces a slight risk of a rare group of serious birth defects known as congenital varicella syndrome. A baby who has congenital varicella syndrome might develop skin scarring, and eye, brain, limb and gastrointestinal abnormalities. If chickenpox develops during the few days before you deliver to 48 hours postpartum, the baby might be born with a potentially life-threatening infection called neonatal varicella.

If you're exposed to chickenpox during pregnancy and you're not immune, contact your health care provider immediately. He or she might recommend an injection of an immune globulin product that contains antibodies to the chickenpox virus. When given within 10 days of exposure, the immune globulin can reduce the risk of chickenpox or reduce its severity. Unfortunately, due to the rareness of congenital varicella syndrome, it isn't clear if this treatment helps protect the developing baby.

If you develop chickenpox during pregnancy, your health care provider might prescribe oral antiviral drugs to speed your recovery. The medication is most effective when given within 24 hours of the rash developing. If you have chickenpox when you deliver, your baby might be treated with an immune globulin product shortly after birth to try to prevent neonatal varicella. If your baby develops chickenpox in the first two weeks of life, antiviral drugs might be given as well.

If you're considering pregnancy and you haven't already had chickenpox or been vaccinated, ask your health care provider about the chickenpox vaccine. It's safe for adults, but it's recommended that you wait until three months after your second dose of the vaccine before trying to conceive. If you're not sure whether you're immune, your health care provider can do a blood test to find out if you're immune or have already had the vaccine.