Fetal Morbidity and Mortality After Acute Human Parvovirus B19 Infection in Pregnancy: Prospective Evaluation of 1018 Cases

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Between one third and two thirds of pregnant women in different parts of the world are susceptible to human parvovirus B19 (B19) infection. Acute infection by B19 during pregnancy has been associated with fetal anemia, hydrops fetalis, nonhydropic intrauterine fetal death, and asymptomatic fetal infection. The major target cells of B19 are erythroid progenitors. This prospective observational study enrolled 1018 pregnant women living throughout Germany in whom acute B19 infection was confirmed by estimating titers of B19 immunoglobulin G (IgG) and IgM antibodies. Fetal mortality was 6.3% in this study. It was 11.0% when infection occurred in the first 20 months of gestation. Only when maternal B19 infection was detected before 20 completed weeks of gestation did fetal deaths occur. The rate of stillbirth was 0.6%. Three of these 6 cases presented with fetal hydrops, and the overall risk of this condition was 3.9%. Intrauterine transfusions were given in 3 of 17 cases of nonsevere hydrops and to 13 of 23 with severe hydrops. All nontransfused fetuses with severe hydrops died, but 11 of 13 severely affected fetuses (84.6%) survived after fetal transfusion. There was no evident correlation between maternal symptoms and the risk of either hydrops fetalis or nonhydropic fetal death. The findings in this, the largest prospective observational study reported to date, confirms generally favorable fetal outcomes in the presence of maternal B19 infection despite an increased risk of fetal death and hydrops. Fetal deaths are mostly limited to those exposed in the first 20 weeks of gestation. Timely intrauterine transfusion lowers the mortality risk for severely hydropic fetuses. B19-related stillbirths are uncommon in the absence of a hydropic presentation.