ABO Incompatibility

ABO incompatibility is a common cause of hemolytic disease in newborns, occurring when there is a blood group mismatch between the mother and the baby. It most frequently arises when a mother with blood group O carries a fetus with blood group A or B. The mother’s immune system produces IgG antibodies against the fetal red blood cell antigens, which can cross the placenta and lead to hemolysis (destruction of red blood cells) in the fetus or newborn.

Unlike Rh incompatibility, ABO incompatibility can occur during the first pregnancy and is generally less severe. However, it may still result in neonatal jaundice due to increased bilirubin production from red cell breakdown. In some cases, mild anemia may also be present. Severe complications such as kernicterus are rare but possible if bilirubin levels are not managed appropriately.

Clinical features typically appear within the first 24–48 hours after birth and include jaundice and sometimes pallor. Diagnosis is confirmed through blood group testing, direct Coombs test, and serum bilirubin levels.

Management focuses on controlling hyperbilirubinemia using phototherapy, and in severe cases, exchange transfusion may be required. Early detection and prompt treatment ensure excellent outcomes in most affected neonates.