Hemolysis of the newborn can occur with any combination of blood types other than O-type combined with each other. Hemolysis of the newborn is caused by the combination of antibodies in the mother’s plasma with antigens on the red blood cell membranes in the newborn’s blood due to the difference in blood types between the newborn and the mother, resulting in an antigen-antibody reaction leading to an increase in the destruction of red blood cells. A child born to a male with type O blood and a female with type O blood can only have type O blood, which is the same as the mother’s blood type. There are neither A nor B antigens on the red blood cell membranes in the blood of a newborn, so no antigen-antibody reaction will occur, and hemolysis of the newborn will not occur. Any combination of blood groups other than this one may occur when the newborn has a different blood type than the mother, so hemolysis of the newborn may occur. Hemolysis of the newborn should be treated with early perinatal intervention to avoid accidents.