PurposeEvaluating procedure-related complications and perinatal outcomes after intrauterine transfusion (IUT) before or after 20+0weeks of gestation in fetuses with severe anemia due to intrauterine human parvovirus B19 infection.MethodsA retrospective study investigating fetuses requiring IUT for fetal Parvo B19 infection in two tertiary referral centers between December 2002 and December 2021. Procedure-related complications, intrauterine fetal death (IUFD), and perinatal outcome were correlated to gestational age (GA) at first IUT, the presence of hydrops and fetal blood sampling results.ResultsA total of 186 IUTs were performed in 103 fetuses. The median GA at first IUT was 19+3(13+0–31+4) weeks of gestation. IUFD occurred in 16/103 fetuses (15.5%). Overall survival was 84.5% (87/103). Hydrops (p= 0.001), lower mean hemoglobin at first IUT (p= 0.001) and low platelets (p= 0.002) were strongly associated with IUFD. There was no difference observed in fetuses transfused before or after 20+0weeks of gestation.ConclusionIUT is a successful treatment option in fetuses affected by severe anemia due to parvovirus B19 infection in specialized centers. In experienced hands, IUT before 20 weeks is not related to worse perinatal outcome.