Fetal morbidity and mortality after acute human parvovirus B19 infection in pregnancy: prospective evaluation of 1018 cases.

OBJECTIVE

To determine more precisely the incidence of fetal complications following maternal parvovirus B19 infection at various gestational ages.

METHODS

An observational prospective study of 1018 pregnant women whose acute B19 infection was serologically confirmed in our laboratory.

RESULTS

The observed rate of fetal death throughout pregnancy was 6.3% (64/1018) (95% confidence interval [CI]: 4.9, 8.0). The fetal death rate for those infected within the first 20 weeks of gestation (WG) was 64/579 (11.0%). Fetal death was only observed when maternal B19 infection occurred before the completed 20 WG. The observed stillbirth proportion was 0.6% (6/960). Three of six stillbirth cases presented with fetal hydrops. The overall risk of hydrops fetalis was 3.9% (40/1018) (95% CI: 2.8, 5.3). Three of 17 cases with non-severe hydrops and 13 of 23 cases with severe hydrops received intrauterine transfusion(s). The proportion of fetuses with severe hydrops that survived following fetal transfusions was 11/13 (84.6%). All of the non-transfused fetuses with severe hydrops died.

CONCLUSION

Our data demonstrate a relevant B19-associated risk of fetal death, which is largely confined to maternal B19 infection in the first 20 WG. Timely intrauterine transfusion of fetuses with severe hydrops fetalis reduces the risk of fetal death. Parvovirus B19-associated stillbirth without hydropic presentation is not a common finding.