Parvovirus in Pregnancy: What You Need to Know

Posted On: January 10, 2017 By Nathan D. Fox, MD

What is Parvovirus?

A common childhood infection, parvovirus B19 is caused by a small, non-enveloped DNA virus that rapidly infects dividing cells. This virus effects the precursors of erythrocytes (red bled cells).

Approximately 30 to 60 percent of adults have prior exposure to parvovirus, which can be diagnosed with antibody testing. Viremia, or the presence of virus in the blood, begins about one week after exposure and continues for one week. IgM antibodies can be detected 10 days after exposure and may last several months after diagnosis. IgG antibodies are found only a few days after IgM antibodies develop, and IgG antibodies may last for years.  The presence of IgG antibodies is indicative of prior exposure as well as immunity.

Parvovirus in Pregnancy

For the mother, parvovirus infection generally causes mild flu-like symptoms. However, the risk of the fetus has received a great deal of attention because initial reports suggest that parvovirus B19 during pregnancy may result in severe fetal anemia and stillbirth. With increasingly expanding red cell volume, a shorter half-life of red blood cells, and a weaker immune system, the fetus is susceptible to the effects of this virus.

Fetal Infection with Parvovirus

For the majority of exposed and infected women, parvovirus is not transmitted to the fetus. The virus is transmitted to the fetus in approximately one-fourth to one-third of maternal infections (and not all exposed women become infected). In a small portion of affected fetuses, the fetus is at risk for transient aplastic crisis, hydrops, high output failure, and fetal death. This occurs in approximately 5 percent of maternal infections.

Managing Parvovirus in Pregnancy

For women with diagnosed parvovirus infection, based on serologic testing, diagnostic ultrasonography testing is used to detect any signs of fetal anemia, which typically occurs within 6 to 8 weeks after the parvovirus infection. If evidence of hydrops develops, the suggested management involves intrauterine transfusion, which is still considered the optimal treatment or management in parvovirus during pregnancy.

Any pregnant woman with possible exposure to parvovirus should consult with her doctor.  Simple blood testing can determine if she is immune, susceptible but not infected, or susceptible and probably infected. The latter group of infected women should undergo serial ultrasounds for approximately 8 weeks after infection with a plan for fetal transfusion should fetal anemia be suspected.  Fortunately, with close follow-up, parvovirus infection in pregnancy usually leads to good fetal outcomes.

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Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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