Perinatal outcomes following in-utero transfusion for hydrops fetalis associated with parvovirus B19 infection

Congenital parvovirus B19 (PB19) infection can lead to severe fetal anemia and hydrops fetalis, necessitating in-utero transfusion (IUT) as a life-saving intervention. This study aimed to identify risk factors associated with unfavorable perinatal outcome following IUT in hydropic fetuses with PB19 infection, with the goal of optimizing transfusion strategies and improving fetal survival.

A retrospective, multicenter, international cohort study was conducted across nine specialized fetal medicine centers in France, Belgium and the Czech Republic. This study included pregnant women with a fetus diagnosed with hydrops due to PB19 infection that underwent at least one IUT for severe fetal anemia between January 2014 and May 2024. Clinical, demographic and procedural data were analyzed. The primary outcome was to identify maternal, fetal, obstetric or IUT-related risk factors associated with adverse fetal or neonatal outcome, defined by a composite criterion of unfavorable outcome that included perinatal mortality and/or severe and persistent fetal anomalies, including severe fetal brain injury at follow-up. Statistical analysis was conducted using logistic regression models to assess potential risk factors.

Of the 84 eligible cases, 78 pregnancies were included in the final analysis. The rate of perinatal survival without severe brain injury was 59.0% (46/78), while 41.0% (32/78) of cases had an unfavorable outcome, including 20 (25.6%) cases of stillbirth, nine (11.5%) cases of termination of pregnancy, one (1.3%) case of continuation of pregnancy despite severe prenatal neurological findings and two (2.6%) cases of neonatal death. Notably, a higher fetal hemoglobin (Hb) level (> 9.3 g/dL) after the first or second IUT was significantly associated with a reduced risk of unfavorable outcome (adjusted odds ratio (aOR), 0.6 (95% CI, 0.4-0.8)). A femur length Z-score of < -2 was associated with unfavorable outcome (aOR, 5.4 (95% CI, 1.3-27.0)). Transplacental vs transamniotic funicular puncture was not significantly associated with perinatal survival.

IUT remains a cornerstone intervention for managing severe fetal anemia caused by PB19 infection; however, rates of perinatal loss continue to be substantial, especially in the presence of severe hydrops. Achieving higher post-transfusion Hb levels appears to be an important factor in improving survival outcomes for hydropic fetuses with PB19 infection. © 2026 International Society of Ultrasound in Obstetrics and Gynecology.