Newborns with positive direct human antiglobulin test who developed hemolytic disease - prevalence at the Professor Doutor Fernando da Fonseca Hospital, EPE

Hemolytic disease of the newborn (HDN) is an immune-mediated condition caused by the transplacental transfer of maternal antibodies against fetal red blood cell antigens, leading to hemolysis and potentially severe neonatal complications. HDN most frequently arises from maternal–fetal blood group incompatibility involving the ABO or Rh(D) systems. Following the introduction of anti-D immunoglobulin prophylaxis, Rh(D)-mediated HDN has significantly declined, making ABO incompatibility the predominant cause in current clinical practice.This analytical cross-sectional observational study aimed to determine the prevalence of direct antiglobulin test (DAT)-positive newborns who developed HDN at Hospital Professor Doutor Fernando da Fonseca (HFF) between 2017 and 2021. The specific objectives were to assess the prevalence of HDN associated with ABO incompatibility, Rh(D) incompatibility, and other alloantibodies, as well as to characterize the antibodies responsible for disease development.A total of 133 DAT-positive newborns were included. Maternal and neonatal immunohematological data and clinical records were retrospectively analyzed using descriptive statistical methods.Overall, 64.7% of DAT-positive newborns developed HDN. The highest proportion was associated with ABO incompatibility, particularly maternal–fetal AO incompatibility. The prevalence of HDN related to ABO incompatibility was 76.2%, whereas Rh(D) incompatibility accounted for 22.7% of cases. No cases associated with other alloantibodies were identified.These findings reinforce the clinical relevance of DAT in the diagnostic assessment of HDN and emphasize the importance of systematic prenatal blood group screening and targeted monitoring of at-risk pregnancies. Early identification of susceptible newborns may contribute to timely diagnosis, appropriate clinical surveillance, and improved neonatal outcomes.