The symptoms of ABO hemolytic disease vary greatly in severity. Mild cases present with only mild jaundice, which can easily be missed as physiological jaundice, and some present with only advanced anemia, while severe cases can develop stillbirth, severe jaundice or severe anemia. Hepatomegaly and nuclear jaundice can be seen in heavy cases, but splenomegaly is rare. Compared to Rh haemolytic disease, the symptoms are milder and the clinical presentation is dominated by jaundice, which appears earlier (24-36h) and deepens more rapidly. Serum bilirubin can reach more than 255 μmol/L (15 mg/dl), and a few exceed 340 μmol/L (20 mg/dl), which can be complicated by bilirubin encephalopathy if not treated in time. The degree of anemia and hepatosplenomegaly are less severe. The occurrence of fetal edema is much less common. Jaundice is the main symptom of ABO hemolytic disease, and most of them appear 2-3 days after birth, and about 1/4 of them appear within the first day after birth. Similarly, those with severe jaundice [total serum bilirubin of 342 μmol/L (20 mg/dl) or more] are also about 1/4. 2, anemia ABO hemolytic disease patients have varying degrees of anemia, but generally to a lesser degree, with severe anemia (referring to hemoglobin below 100g/L) accounting for only about 5%. In some mild cases of ABO hemolytic disease, the early symptoms may not be severe, but late anemia occurs 2-6 weeks after birth, or the anemia is particularly severe during the “physiological anemia” period 8-12 weeks after birth, which is due to the persistence of antibodies and the occurrence of chronic hemolysis. Blood group antibodies can shorten the life span of red blood cells. It has been reported that the life span of erythrocytes in these children is only about 35 days, and the daily decrease in hemoglobin is about 4 times that of normal children in the same period, and the destruction of erythrocytes increases, while the bone marrow hematopoietic function is physiologically low at this time and cannot compensate effectively, resulting in neonatal late anemia. According to the clinical manifestation and laboratory examination, the diagnosis can be confirmed by the ABO blood group incompatibility between mother and infant, plus a positive index of red blood cell sensitization (modified direct Coombs test or antibody release test). 1. Prenatal diagnosis (1) Parental blood group determination: Any mother with previous history of unexplained miscarriage, preterm birth, stillbirth, stillbirth, or history of severe neonatal jaundice should be alerted to the presence of maternal-infant blood group incompatibility. The blood type of the mother and father should be determined, and in cases of parental blood group incompatibility, the blood group antibodies of the mother should be determined. (2) Determination of maternal blood group antibodies: Pregnant women suspected of having possible fetal hemolytic disease should undergo anti-blood group antibody determination. The first measurement is usually performed in the fourth month of pregnancy, which can be used as a base level of antibodies. The first measurement is usually performed in the fourth month of pregnancy, which can be used as a base level of antibodies. Subsequent measurements will be performed once a month, once every half month during the seventh to eighth month of pregnancy, and once a week after the eighth month. If the antibody potency rises, fluctuates or changes from high to low, it suggests that the child may be involved. Since substances similar to A and B antigens exist in nature, natural anti-A or anti-B antibodies may exist in the mother’s body, and an antibody potency of 1:64 for ABO hemolytic disease is usually considered a suspicious case. The mother’s antibody potency remains unchanged, suggesting stable disease. (3) Amniotic fluid examination: normal amniotic fluid is colorless and transparent, while amniotic fluid in severe hemolytic disease is yellow-green. The more severe the fetal hemolysis, the higher the amniotic fluid bilirubin content, so the amniotic fluid bilirubin content can be used to estimate the condition and decide to terminate the pregnancy. The optical density of amniotic fluid at a wavelength of 450 nm is correlated with the bilirubin content in amniotic fluid, and the optical density of amniotic fluid at a wavelength of 450 nm can be determined by spectrophotometer to represent the level of bilirubin in amniotic fluid. As the content of bilirubin in amniotic fluid decreases with increasing gestational weeks, the number of increases in optical density measured at different gestational weeks has different significance. The fetal liver and spleen are large, and fluid accumulates in the chest and abdomen. 2, postnatal diagnosis (1) clinical manifestations: observe whether the newborn has hemolytic symptoms such as anemia, edema, jaundice and hepatosplenomegaly, if so, neonatal hemolytic disease should be considered. (2) Laboratory tests: for newborns with edema, anemia at birth, jaundice within 24h after birth and Rh-negative mothers should be considered neonatal hemolytic disease, routine blood tests, maternal and infant blood groups, serum bilirubin and Coombs test should be done.