Chicken Pox in Pregnancy

While most pregnant women (80-90%) are protected from chicken pox due to previous infection, women who are pregnant and who have not previously had chicken pox worry about getting the infection and what complications it may cause to the pregnancy.

Chicken Pox Symptoms

Chicken pox is caused by the varicella-zoster virus. Chicken pox is so common partly because it is so infectious. It's spread through water, in the air and through physical contact, and it causes a fever and an itchy rash characterized by small itchy red bumps (or "pox") that crust over before healing.

The incubation period for chicken pox is two weeks, meaning someone can have this infection and not even know it for two weeks before symptoms appear. It's contagious two days before the rash appears to after the pox crust over.

Risks to Mom

If you have already had chicken pox, you cannot contract it again and there is no risk to you or the baby if you come into contact with the virus. If there's any doubt as to whether or not you are immune, see a doctor for a blood test.

If you do contract chicken pox during your pregnancy, you are at a greater risk for chicken pox pneumonia by as much as 10%. This can be very severe and even life threatening.

Risks to Baby

If you get chicken pox while you're pregnant, your baby is at the most risk during two times:

1. If you get chicken pox before 20 weeks, especially if it's between weeks 8-12, there is a 2.2% risk of your baby getting congenital varicella syndrome. This can cause permanent scarring on the skin and also other abnormalities such as a smaller than normal head, eye problems, low birth weight, small limbs, and mental retardation.

2. If chicken pox occurs within a week before delivery up to a month afterwards, the baby has a risk of developing disseminated varicella infection because Mom's antibodies did not get a chance to be passed to the baby. Infant death from this overwhelming infection happens in 25% of cases.

Between 20 weeks and term there is no risk to the baby.

Getting Treatment

If you are not immune to chicken pox and have been exposed to it during the times when it is risky for your baby, it is important to give Varicella-Zoster Ig ('man-made' antibodies) to mum and/or baby. This can be lifesaving and significantly reduce the disease severity. It must be given no later than 10 days after exposure to the chicken pox virus.