Neonatal hemolysis does not occur when the mother is blood type B and the father is blood type O. Because neonatal hemolysis is prone to occur when the mother is blood type O and the father is blood type A, B or AB, the immune hemolytic disease caused by blood group antigen immunity due to mother-infant blood group incompatibility is called ABO hemolytic disease. When the mother’s blood type is O and the fetus’ blood type is A or B, the A and B antigens in the fetus’ blood enter the mother’s body and stimulate the mother to produce blood group antibodies. This antibody then enters the fetus through the placenta and combines with the A and B antigens in the fetus, causing fetal red blood cell agglutination and subsequent lysis and hemolysis, resulting in edema, anemia, hepatosplenomegaly and progressive aggravation of severe jaundice within a short time after birth. When the mother is a B blood type and the father is an O blood type, hemolytic anemia will not occur.