In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to chickenpox, shingles may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is chicken pox?

Varicella, commonly called chicken pox, is a viral infection that usually happens in childhood. Chicken pox is caused by the varicella-zoster virus (VZV).

The most common symptom of chicken pox is a rash, which first appears as small, reddish spots or pimples. These spots will blister and then scab over. New spots appear for up to 3-5 days. Often a fever and body aches occur before the rash appears. Pneumonia also occurs in 10-15% of teenagers and adults who have chicken pox.

Is chicken pox contagious?

Yes, chicken pox is very contagious, meaning it can spread easily from person to person. A person who has chicken pox is contagious 1-2 days before they break out in their rash and continue to be contagious until all of their spots are scabbed over. If you have never had chicken pox before, there is a 90% chance that you will catch it if someone in your house has it. Infection occurs less often after exposure in other places, such as a school. People develop symptoms about 7-21 days after being exposed to chicken pox.

I am pregnant and I don’t think I ever had chicken pox and have recently been exposed. Is there anything I can do?

Have your health care provider do a blood test to see if you have any antibodies to the chicken pox virus. Up to 95% of women who do not think or know if they ever had chicken pox will have antibodies on a blood test, which means that they have previously had chicken pox.

You are not immune (have not been exposed in the past) if a blood test shows that you do not have antibodies to the chicken pox virus. If you are not immune, you are at risk for being infected if exposed to the virus. Women who become infected with chicken pox for their first time during pregnancy often have more severe symptoms than adults who are not pregnant.

If you have been recently exposed to someone with chicken pox and you do not have immunity, discuss with your health care provider the steps that you can take to try to avoid developing the disease or to reduce the severity of symptoms; such as getting the varicella zoster immune globulin shot (VariZIG) or taking oral antiviral medication. VariZIG is a blood product that contains high levels of chicken pox antibodies. Some experts say that chicken pox is more severe in pregnancy and recommend nonimmune pregnant women to get this type of shot after a direct exposure. The shot should be given as soon as possible within 4 days of the first exposure. It is unknown whether VariZIG will help prevent chicken pox infection in the fetus. VariZig has been used in babies, including preterm infants.

I’m pregnant and have just been exposed to chicken pox. I had chicken pox when I was a child. Is there risk to my baby?

Unlikely. When a person has chicken pox, he/she makes antibodies to the virus. These antibodies last a long time and keep a person from getting chicken pox again (become immune). People who are immune most likely will not develop chicken pox if they are exposed to the virus again.

I had chicken pox at 10 weeks of pregnancy. Does my baby have an increased chance for birth defects or other pregnancy complications?

The studies show that the risk is small and most all babies born to women who have chicken pox in pregnancy are healthy. About 1-3 % of the babies whose mothers had chicken pox in pregnancy have one or more birth defects due to the infection called congenital varicella syndrome. The birth defects include scars, eye problems, poor growth, underdevelopment of an arm or leg, small head size, or delayed development and/or intellectual disability. Some babies may have only one of these problems while others have some or all.

The greatest chance for problems to occur in the developing baby is when the mother develops chicken pox between 7 and 20 weeks of pregnancy. It is also more common for preterm delivery (baby is born before week 38) to occur when a mother develops chicken pox in the first half of the pregnancy. The chance for birth defects due to chicken pox infection in the first trimester of pregnancy is 0.5-1%. When chicken pox occurs between 13 and 20 weeks of pregnancy, the chance for birth defects appears to be up to 2%.

Is there any prenatal screening that I can have in pregnancy to see if my baby has birth defects from my chicken pox infection?

Discuss screening options with your health care provider. They may discuss ultrasound scans in your pregnancy to screen for birth defects, growth of the baby, and to monitor fluid levels. Ultrasound cannot pick up all birth defects that can be caused by chicken pox in pregnancy.

My due date is in 3 weeks, and I have just been exposed to chicken pox. Is there any risk to my baby if I develop chicken pox at this stage of pregnancy?

If you already had chicken pox or had the vaccine, you do not need to be concerned because your prior infection should protect you.

If you have not had the chicken pox or had the vaccine in the past, talk to your doctor right away.

If you develop chicken pox 5 days or less before delivery or 1-2 days after delivery, there is a 20-25% chance your newborn baby could also develop chicken pox. Chicken pox infection in this time period is called neonatal varicella. Neonatal varicella can be severe.

If you develop chicken pox between 6 and 21 days before delivery, there is still a chance your newborn could develop neonatal varicella. However, because your baby will get some of your newly-made chicken pox antibodies, the neonatal varicella will probably be mild.

What is shingles?

Shingles is common. About 1 in 3 Americans gets shingles in their lifetime. Over half of the people that get shingles are over 60 years of age. Shingles is rare in pregnancy.

After someone has chicken pox, the virus remains inactive in the nerves of the spine and cranial nerve ganglia. If the virus in the body is activated again, it causes shingles, also known as herpes zoster. Shingles appears as painful blisters that are usually only on a small area of the body. Shingles can also lead to skin infections, nerve pain, and hearing or vision problems.

My co-worker has shingles. Is there any risk to my baby?

Shingles is not passed to other people, but if you have contact with (touching) the blisters and you have never had chicken pox (varicella), it is possible to get infected with chicken pox this way.

If you have had chicken pox or had the vaccine, you have antibodies to the chicken pox virus and these antibodies protect you.

I’m 8 weeks pregnant and just developed shingles. Can shingles harm my baby?

In a large study of chicken pox exposure during pregnancy, there was no evidence of fetal harm in 366 pregnant women who developed the shingles.

I have the chicken pox and am breastfeeding my baby. Do I need to stop breastfeeding?

No. The chicken pox virus has not been found in breast milk of women with a chicken pox infection. Breast milk may contain antibodies that can protect your baby from getting the chicken pox. Because chicken pox is very contagious, talk to your child’s pediatrician right away if you come down with the chicken pox. Trying to prevent your baby from coming into direct contact with your rash will lower the chance of your baby getting infected.

I am immune to chicken pox, but what if the father of the baby is infected?

There are no studies looking at possible risks to a pregnancy when the father has chicken pox. Infection of the father is unlikely to increase the risk to a pregnancy. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at https://mothertobaby.wpengine.com/fact-sheets/paternal-exposures-pregnancy/pdf/.

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