Can Exposure to Chickenpox During Pregnancy Cause a Miscarriage?

Mom holding baby with chicken pox

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Chickenpox, aka varicella, was once a common childhood infection. Most children nowadays receive a vaccination against chickenpox, but the virus is still circulating in the population.

For most people, chickenpox is no reason to panic. Most children who contract the virus do not have serious complications; adults can be somewhat more uncomfortable, but usually recover from the illness without severe problems.

Complications for Pregnant Women With Chickenpox

Among the rare pregnant women who are not already immune, exposure to varicella during pregnancy can cause complications. About 10% to 20% of infected pregnant women can develop a condition called varicella pneumonia. Women who are immune are generally not at risk for complications, and about 85% to 95% of women are immune.

Miscarriage and stillbirth can also occur after a mother contracts chickenpox during pregnancy, but based on the limited available data, non-immune moms exposed to chickenpox in the first trimester do not appear to have increased rates of miscarriage compared to the general population. The primary concern in contracting varicella during pregnancy is the risk of congenital birth defects—and even in this respect, there's no cause to panic quite yet even if you have been exposed.

Although birth defects from chickenpox exposure (congenital varicella syndrome) can be severe, the risk of a baby having birth defects due to chickenpox exposure in the first half of pregnancy is between 0.4% to 2%. Exposure in the second half of pregnancy would not be likely to result in birth defects.

Complications for the baby are unlikely if chickenpox exposure occurs between the 20th to 36th week of pregnancy, although the mother can face health risks. The baby faces the highest risk if exposure to chickenpox occurs during the last month of pregnancy. In these cases, the baby can develop chickenpox in the womb.

This would be neonatal rather than congenital varicella. Neonatal varicella does not involve birth defects but instead a systemic disseminated infection with very high mortality rates. There is a substantial risk of neonatal death if the baby is born with chickenpox.

When to See a Doctor

Women concerned about exposure to chickenpox during pregnancy should speak with their doctor immediately. Your doctor can order a blood test to determine whether or not you are already immune to chickenpox.

If not, your doctor can decide on a course of action. Your doctor may wish to give varicella-zoster immune globulin (VZIG) if you have been exposed and are not immune, or they may prescribe an anti-viral medication such as Acyclovir.

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  1. Centers for Disease Control and Prevention. Varicella. Updated April 15, 2019.

  2. March of Dimes. Chickenpox during pregnancy. Updated December 2014.

  3. Royal College of Obstetricians and Gynaecologists. Chickenpox and pregnancy. Updated June 2015.

  4. Lamont RF, Sobel JD, Carrington D, et al. Varicella-zoster virus (chickenpox) infection in pregnancyBJOG. 2011;118(10):1155-1162. doi:10.1111/j.1471-0528.2011.02983.x