Parvovirus B19 (Fifth Disease) in Pregnancy
The short answer
Fifth disease (caused by Parvovirus B19) is usually mild in adults but can pose risks during pregnancy, including fetal anemia and hydrops fetalis in rare cases. About 50-60% of adults are already immune from childhood exposure. If you are exposed during pregnancy, blood testing can determine your immunity status and guide monitoring.
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By Age
What to expect by age
Parvovirus B19 infection in the first trimester carries a slightly higher risk of miscarriage. If you are exposed (often through school-age children), your provider can test for immunity. If you are already immune (positive IgG, negative IgM), there is no risk. If you are susceptible and infected, the overall risk of serious fetal complications is about 5-10%.
The second trimester (13-20 weeks) is the period when the fetus is most vulnerable to parvovirus-induced anemia. If infection is confirmed, serial ultrasounds (weekly or every 1-2 weeks) are recommended to monitor for signs of fetal anemia. The peak risk for fetal complications is 4-6 weeks after maternal infection.
Fetal risk decreases in the third trimester. If infection occurs, monitoring with ultrasound is still recommended. Most infected pregnancies result in healthy babies, even without treatment. In severe cases of fetal anemia, intrauterine blood transfusion can be life-saving.
What Should You Do?
When to take action
- Being immune to parvovirus from previous exposure (positive IgG antibodies)
- Having been exposed but testing showing immunity
- You have been exposed to someone with fifth disease (rash illness in a child)
- You work with young children and there is an outbreak
- You develop a rash, joint pain, or flu-like symptoms after exposure
- Confirmed acute parvovirus infection during pregnancy - specialist referral needed for monitoring
- Ultrasound showing signs of fetal hydrops or anemia
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
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