The study aimed to develop structured, expert-based clinical guidance on the prenatal and postnatal management of hemolytic disease of the fetus and newborn. A Delphi procedure was conducted among an international panel of experts in fetal medicine, neonatology, and hematology. Experts were selected based on their expertise, relevant publications, and affiliations. The domains were (i) prenatal workup, (ii) prenatal monitoring and management, (iii) intrauterine transfusion (IUT), (iv) delivery, and (v) postnatal management. The predefined cut-off for consensus was ≥70% agreement. One hundred-seven experts representing 25 countries across 6 continents completed the first round, and 100 (93.5%) completed the subsequent rounds. 75.3% agreed on using cfDNA to determine fetal antigen status, particularly for RhD, Kell, and Rhc antigens. The critical titer, requiring fetal monitoring via ultrasound, is considered when the threshold of ≥16 is for non-Kell antigens. 70.0% agreed on the use of maternal IVIg in pregnancies with prior IUT <
24 weeks or fetal/neonatal death due to HDFN. The minimum GA for IUT is 16 to 18 weeks, and the maximum is 35