Assistant Professor of Pediatrics Intermountain Health/University of Utah Salt Lake City, Utah, United States
Background: Advances in the prevention and treatment of Rh(D) alloimmunization have been one of the great success stories of modern obstetric, fetal, and neonatal medicine. Nonetheless, alloantibodies to Rh(D) and non-Rh(D) red blood cell antigens are seen in as many as 4% of pregnancies and can result in hemolytic disease of the fetus and newborn (HDFN). Objective: To evaluate neonatal outcomes from all deliveries in Intermountain Health hospitals during a five-year period in which the mother had a positive antibody screen. Design/Methods: We identified all deliveries between January 1, 2017 and December 30, 2022 in which the mother had a positive antibody screen anytime during the pregnancy. The electronic medical record of each pregnancy (mother and baby) was reviewed by a member of the research team. We verified whether the diagnosis of alloimmunization was correct and collected other pertinent information and outcomes. Results: 707 neonates were born to 705 mothers with positive antibody screens during the pregnancy (incidence 3.0 per 1000 live births or 0.3%). We excluded 31 neonatal cases (4.4%) where the mother’s positive antibody screen was positive due to RhIG and no other antibodies. Three of these had a positive DAT that could not be explained by a cause other than RhIG, but none of the 3 required phototherapy or developed anemia). Of the 676 neonates remaining, 171 (25.3%) had a positive DAT. We determined that 174 neonates in the cohort (25.7%) were antigen-positive for at least one antibody the mother had. HDFN was most severe in cases of alloimmunization due to Rh group antibodies. The risk of NICU admission for hyperbilirubinemia was highest in Anti-D cases (64.3% of antigen-positive neonates born to mothers with anti-D). The risk of receiving a RBC transfusions or an exchange transfusions or both in neonates born to mothers with positive antibody screens was 4.1%. All were in cases of Rh-group alloimmunization. No neonates born to mothers with anti-M, anti-S, anti-Duffy, anti-Kidd A, or anti-Lewis required NICU admission for hyperbilirubinemia, RBC transfusion, or exchange transfusion.
Conclusion(s): Approximately 25% of neonates born to mothers with positive antibody screens were antigen-positive. Antigen-positive neonates born to mothers with Rh-group antibodies were at highest risk of hyperbilirubinemia, NICU admission for hyperbilirubinemia, and other complications. Diligent surveillance and management of these neonates is required to identify those with complications and avoid kernicterus spectrum disorders.
