Abstract
BACKGROUND/OBJECTIVES: Pregnancies complicated by red cell alloimmunization can progress to hemolytic disease of the fetus and newborn (HDFN), requiring close monitoring and timely intervention to prevent fetal/neonatal morbidity and mortality. This study investigated disease presentation, interventions, and outcomes in respondents with a history of alloimmunized pregnancy. METHODS: This was a retrospective cross-sectional survey study administered online to alloimmunized patients between November 2022-February 2023. A total of 127 participants reported on 200 alloimmunized pregnancies. Distribution of pregnancy characteristics, antibodies and titers, monitoring, treatments and fetal outcomes were described and stratified where appropriate by fetal antigen status and disease severity. Outcomes and management practices in subsequent pregnancies following fetal loss to HDFN are reported. RESULTS: Multiple antibodies were present in 42% of pregnancies with known antibody type (80/192). Titers reached critical levels (any titer for Anti-K; ≥16 for all other antibodies) in 71% (125/176) of pregnancies where titer was reported. Among fetal antigen positive pregnancies with critical titers, intrauterine transfusions were conducted in 40% (42/106), intravenous immunoglobulin was administered in 14% (15/106), plasmapheresis in 7% (7/106), and phenobarbital in 9% (9/106). Complications from transfusion were reported in 38% of pregnancies receiving intrauterine transfusion (17/45). Fetal death due to HDFN or complications from intrauterine transfusion was reported in 9% of antigen positive pregnancies with critical titers (10/106) and 16% of pregnancies receiving intrauterine transfusion (7/45). CONCLUSIONS: Disease presentation and severity complements previous research in this disease population, however, monitoring practices were diverse. Fetal death and intrauterine complication rates were higher than those previously reported in large international referral centers. Development of best practices and centralized referral centers may improve disease outcomes.