If the father is blood type O and the mother is blood type B, there will be no hemolysis in the newborn. Hemolysis of the newborn is only prone to occur when the mother has blood type O and the father has non-O blood type. Immune hemolytic disease caused by immunity to blood group antigens due to discordance between the mother’s and baby’s blood groups is called ABO hemolysis. When the mother’s blood type is O and the fetus’s blood type is non-O, the antigen in the fetus’s blood enters the mother’s body and stimulates the mother to produce blood group antibodies. And this antibody re-enters the fetus through the placenta and will combine with the antigen in the fetus, causing red blood cells to agglutinate and thus dissolve to form hemolysis. So when the mother’s blood type is not O, she will not have antibodies and naturally will not cause hemolysis in the newborn.