The Risks of Chickenpox Exposure During Pregnancy

Mom holding baby with chicken pox

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Chickenpox, which is caused by the varicella-zoster virus (VZV), was once a common childhood infection. The disease causes an itchy rash, blisters, and fever, and puts people at risk for developing shingles (a related condition) later in life.

Most children nowadays receive vaccination against chickenpox, but the virus is still circulating in the population because it is highly contagious and some families choose not to (or are unable to) vaccinate their children.

Chickenpox can be risky in pregnancy if the mother is unvaccinated and has not already had the disease. Most likely, it will not cause miscarriage, but it can cause birth defects and stillbirth, depending on the timing of exposure and other factors.

Overview

For most people, particularly children, chickenpox does not usually cause serious disease. Adults tend to have more severe cases.

However, the fever, body aches, and rash caused by the infection can become quite uncomfortable for both children and adults, depending on the severity of the infection. For some groups, including pregnant women, infants, and immunocompromised individuals, chicken pox can cause dangerous complications.

Pregnancy Complications

Approximately 90% of women are already immune to chickenpox at the time of pregnancy, due to infection or vaccination earlier in life. The incidence of chickenpox infection is estimated to be between 0.7 and 3 out of every 1,000 pregnancies.

Among the rare pregnant women who are not already immune, exposure to varicella during pregnancy can cause serious complications. Women who are immune are generally not at risk for any complications.

Varicella Pneumonia

About 10% to 20% of infected pregnant women can develop a condition called varicella pneumonia. Complications include severe breathing problems, which can result in hospitalization, the need for mechanical ventilation, and death. In severe cases, the mortality rate is estimated to be between 3% and 14%.

Miscarriage and Stillbirth Risk

Miscarriage and stillbirth may also occur after a mother contracts chickenpox during pregnancy, but based on the limited available data, non-immune people exposed to chickenpox in the first trimester do not appear to have increased rates of miscarriage compared to the general population.

Congenital Varicella Syndrome

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 only 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.

Neonatal Varicella

The baby faces the highest risk when exposure to chickenpox occurs during the last month of pregnancy. In these cases, the baby can develop chickenpox in the womb or soon after birth. This would be neonatal rather than congenital varicella. Neonatal varicella does not involve birth defects but instead a systemic disseminated infection.

Around 50% of babies whose mothers get chickenpox end up getting it themselves, and the infection tends to be particularly severe in premature babies. 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 Zovirax (acyclovir).

A Word From Verywell

If you are already immune to chickenpox, you can rest assured that your baby is protected if you get exposed to someone with the infection. If you're not immune, your baby will most likely be fine. However, seek care from your doctor straight away to ensure you get the best care.

If you're not already immune and not already pregnant, but hope to be soon, aim to get vaccinated for chickenpox first. The very real risk of health complications for mom as well as birth defects and stillbirth underscore the importance of getting all your vaccines to protect everyone's health and safety—in your family and that of the community at large.

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

  2. Centers of Disease Control and Prevention. Complications. Reviewed December 31, 2018.

  3. 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

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

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