Parvovirus B19 infection in pregnancy: perinatal outcomes derived from a systematic review and meta-analysis

Objective: The main aim of this study was to evaluate fetal and perinatal outcomes of Parvovirus B19 infection in pregnancy, focusing on the differences between characteristics of the recent disease outbreak (2023-2024) compared to the previous waves. The results should inform clinical management strategies by providing an updated and comprehensive assessment of the literature. Data sources: MEDLINE, Embase, Scopus, Web of Science, Cochrane Library, and CINAHL databases, from 2000 to April 2025. Study eligibility criteria: Studies including cases of maternal and/or fetal Parvovirus B19 infection, reporting perinatal outcomes, were included. Synthesis method: We performed a meta-analysis of pooled proportions using a random-effects model; for dichotomous outcomes, logit-transformed proportions were analyzed using generalized linear mixed models. For continuous outcomes (cumulative mean values), random-effects models of mean differences were applied. All outcomes were described in the study cohort, and a second analysis comparing cases from the most recent wave (2023-2024) and older cases was also performed by random-effects meta-regression analysis. Results: Forty-four studies were included in the final analysis, and the total study population encompassed 3221 women and 748 fetuses with Parvovirus B19 infection. The rate of intrauterine demise among fetal infections was 38.7% (95% confidence interval, 27.3-51.6), whereas among maternal infections it was lower (7.3%; 95% confidence interval, 4.6-11.3). Intrauterine transfusion was performed in 34.9% of cases (95% confidence interval, 21.9-50.7) of fetal infections and in 15.3% of cases of maternal infection (95% confidence interval, 7.9-27.6). Ultrasound signs of anemia among infected fetuses included hydrops (58.7%; 95% confidence interval, 38.8-76.2), cardiomegaly (39.0%; 95% confidence interval, 26.3-53.4), hepatic involvement (10.8%; 95% confidence interval, 6.1-18.4), and fetal growth restriction (9.5%; 95% confidence interval, 5.0-17.2). The rate of abnormal neuroimaging was high among fetuses that had prenatal magnetic resonance imaging (28.6%; 95% confidence interval, 17.0-43.9). No significant difference was observed in the rate of intrauterine demise (odds ratio, 0.84; 95% confidence interval, 0.46-1.54; P=.58) or ultrasound signs of fetal anemia (odds ratio, 1.13; 95% confidence interval, 0.82-1.56; P=.46) between the new and the previous waves. The rate of intrauterine transfusions was higher in the recent wave; however, statistical significance was not reached (odds ratio, 1.74; 95% confidence interval, 0.90-3.34; P=.09). Conclusion: Parvovirus B19 infection in pregnancy is associated with high perinatal morbidity and mortality. Nevertheless, no significant differences were observed in the rate of intrauterine demise during the recent outbreak of the disease (2023-2024) compared to the previous waves. In clinical practice, findings from this systematic review can inform patients about the rate of adverse outcomes, depending on their status (maternal or fetal infection or fetal infection requiring intrauterine transfusion). In cases of maternal infection, the rate of intrauterine demise is much lower than that in the case of confirmed fetal infection. Finally, the high rate of abnormal brain findings when fetal magnetic resonance imaging was performed in cases of intrauterine transfusion may be relevant to clinicians as reflecting the potential role of adding this second-level imaging method to improve prenatal diagnosis of these cases. Large multicenter studies are needed to evaluate the impact of prenatal therapeutic interventions and the role of prenatal neuroimaging in these cases.