Severe hemolytic disease of the newborn in a group B African-American infant delivered by a group O mother.

Maternal-fetal ABO incompatibility is a common hematological problem affecting the newborn. In general, hemolysis is minimal and the clinical course is relatively benign, rarely causing the escalating levels of hyperbilirubinemia and significant anemia commonly associated with Rh hemolytic disease of the newborn (HDN). The incidence of HDN ranges from one in 150 births to 1:3000 births, depending on the degree of anemia and level of serum bilirubin.