If the mother's ABO blood type is O and the father is not, then the baby born in the future is unlikely to suffer from ABO hemolysis. When the mother is type O blood and the fetus is type A or B, anti-A or anti-B antibodies can be produced in the mother, and hemolysis can occur when the mother enters the fetus with blood flow. When ABO hemolysis occurs, the mother must be O type, and when the father is A type, B type or AB type, the fetus may be A type or B type, leading to hemolysis. Of course, if the blood type of the father is O or A2, the blood type of the fetus may be O or A2, even if the mother is O, it will not cause blood type incompatibility.