ABO hemolytic disease of newborn : Does newborn's blood group a risk factor?

Due to the marked decline of maternal-fetal rhesus incompatibility, ABO alloimmunization has become the leading cause of the newborn hemolytic disease. It is estimated that 15-25 % of all pregnancies are concerned by ABO incompatibility.

Neonatal blood group B seems to be more predisposing to acute hemolysis and severe hyperbilirubinemia. We propose to find if the newborn's blood group B represents a risk factor for severe hemolysis and/or severe hyperbilirubinemia.

We conducted a comparative study in the pediatrics department "B" of the Children Hospital of Tunis. We collected retrospectively the medical files of the newborn hospitalized for ABO alloimmunization (January 2011 - March 2014), then we compared two groups, OA group with OA alloimmunization and OB group with OB alloimmunization. A significant threshold was fixed to 0.05.

We collected 98 cases of newborn ABO hemolytic disease. Both groups, OA and OB, were similar for the onset of jaundice, age of hospitalization, initial hemoglobin and indirect bilirubin levels. There were no statistically significant difference in the severity of hyperbilirubinemia and the use of exchange transfusion for the two groups. However, transfusion was statistically more frequent in the OB group compared to OA group (81.6‰ vs 10.2‰, p = 0,039, OR=2.9, 95% IC (1.1 - 7.8)).

OB alloimmunization seems to induce more active hemolysis than OA one, with no difference for severe hyperbilirubinemia in both groups.