Neonatal hemolysis is caused by fetal or neonatal hemolysis caused by ABO blood group incompatibility or RH blood group incompatibility between mother and fetus, mainly manifested by yellow skin staining and anemia. The blood type of the fetus is determined by both parents. If the fetus inherits antigens from the father’s blood type that the mother does not have, during pregnancy, the fetal red blood cells enter the mother’s body and cause the mother to produce the corresponding antibodies, which reach the fetus and hemolysis occurs. For example, if a mother with O blood type is pregnant with a fetus with A blood type, during pregnancy, certain reasons cause abnormal permeability of the placenta, and the A red blood cells in the fetus will enter the mother’s body in small amounts many times, thus causing the mother’s body to produce a large number of antibodies that can destroy the A red blood cells. These antibodies, because of their small molecular weight, can freely enter the fetus through the placenta and destroy the fetal or neonatal red blood cells, resulting in hemolysis, yellow staining and anemia, which is called neonatal hemolytic disease.