The genetic material of the fetus is derived from the mother and father, and fetal red blood cells may carry antigens from the father, manifesting as a fetus with a different blood type than the mother. If the mother and fetus have different blood types, the fetal blood group antigen enters the mother and sensitizes the mother to produce specific alloimmune antibodies, which can enter the fetal circulation through the placenta and bind to the red blood cell antigen, resulting in fetal hemolysis and anemia, and in severe cases, immune fetal edema and even stillbirth, called maternal-fetal blood group incompatibility hemolytic disease, i.e. fetal red blood cell alloimmune hemolysis. The incidence of ABO blood group incompatibility is high, but the incidence of fetal hemolysis is low, and even if the fetus is hemolyzed, the symptoms are often mild and no special treatment is needed during pregnancy. Rh blood group incompatibility is relatively rare, but it can lead to severe fetal anemia and thus requires intervention, and requires close monitoring and timely management during pregnancy.