Hemolytic disease of the newborn may occur when the mother has type O blood and the father has type A blood. Mother’s blood type O, father’s blood type A, the birth of the child is not obvious harm, if the newborn’s blood type is not compatible with the mother, may occur ABO hemolytic disease. ABO hemolytic disease is mainly manifested by jaundice and anemia, and very rarely there may be enlarged liver and spleen. Only if the newborn has severe hemolysis, it can cause bilirubin encephalopathy, which is a more serious complication and may leave cerebral palsy and intellectual backwardness. However, neonatal hemolytic disease can be avoided as long as it is detected in time and with regular treatment, such as phototherapy, medication, and blood exchange therapy, complications can be avoided. Mothers with type O blood, newborns should be tested for hemolytic conditions after birth, and proactively take precautions.