Severe late anemia of hemolytic disease of the newborn

Late anemia is a well-recognized complication of Rhesus hemolytic disease of the newborn (HDN). The incidence of Rhesus HDN is declining, with a tendency for more severely affected pregnancies to be managed in specialist centres. Consequently, many paediatric departments may see relatively few affected infants with comparatively mild disease, and the risk of late anemia in such cases may not always be appreciated. Two cases of infants born with evidence of Rhesus isoimmunization noted at birth and encountering no immediate problems other than mild hyperbilirubinemia are described. After an uneventful early neonatal course, both infants were discharged without follow-up and presented in the second to third weeks of life with severe, life-threatening anemia, leading to neurological sequelae in one case. The importance of close surveillance, including hemoglobin measurements, in all infants with Rhesus hemolytic disease, irrespective of initial severity, is reiterated.