Hemolytic Disease of the Fetus and Newborn

Hemolytic disease of the fetus and newborn (HDFN), also known as erythroblastosis fetalis, is a complex and potentially life-threatening condition arising from maternal-fetal blood group incompatibility. When a fetus inherits paternal blood group factors that are absent in the mother, antepartum or intrapartum fetal-maternal bleeding can provoke a maternal immune response. This immune reaction produces maternal antibodies, a process known as alloimmunization, which can result in varying degrees of transplacental passage of these antibodies into the fetal circulation. Depending on the antigenicity and amount of antibodies involved, this transplacental transfer can lead to hemolytic disease in the fetus and neonate, presenting with complications including anemia, jaundice, and, in severe cases, hydrops fetalis or hyperbilirubinemia and kernicterus in the newborn. Despite significant advancements in the understanding and management of HDFN, the condition remains a significant cause of perinatal morbidity and mortality if left undiagnosed and untreated. However, with the advent of Doppler ultrasonography, noninvasive methods for managing alloimmunization in pregnant women have emerged, supplementing established protocols for HDFN management. These advancements offer a more thorough and less invasive approach to assessing fetal well-being, reducing risks to both the mother and fetus. Additionally, the intricate nomenclature of the Rh blood group system adds complexity to the management of Rh alloimmunization, necessitating a clear understanding of antigenic variants and their implications for clinical practice. Therefore, enhanced knowledge of the pathogenesis, prevalence, prevention, and management strategies of HDFN, as well as the importance of timely intervention and the role of evolving diagnostic techniques in improving outcomes for affected pregnancies.