In addition to the most familiar ABO blood group system, the Rh blood group system is also one of the most important blood group systems, which is very complex and contains 45 different antigens, of which the D antigen is the most important. According to the presence or absence of D antigen on red blood cells, red blood cells can be classified as Rh-positive or Rh-negative. The vast majority of Han Chinese are Rh-positive, and only about 0.4% are Rh-negative, which is relatively rare, so some people jokingly call Rh-negative blood “panda blood”. People who have donated blood or had their blood type medically tested may have the opportunity to know their blood type: e.g. B(-), which has two parts: their ABO blood type system is B, and their Rh blood type system is negative. If a blood transfusion is needed, it is necessary to find blood that matches both blood types in order to transfuse it, so as not to trigger the risk of hemolysis due to blood group incompatibility. As a mother-to-be, it is very necessary to know her own blood type first, because the baby’s blood type is inherited from both parents. If the mother’s blood type is rare and the baby and the mother’s blood types do not match, especially the Rh blood type, there is a risk of intrauterine hemolysis of the fetus, or even intrauterine death. Therefore, when a pregnant woman goes to the hospital for her first maternity checkup, the doctor will first recommend that the mother-to-be be tested for her blood type. If the test reveals that the mother’s blood type is negative and the husband’s blood type is Rh-positive, there is a high possibility that the baby’s blood type is Rh-positive. The mother and baby have their own blood circulation, and although there is a placental barrier between them, many substances can cross the barrier. The baby’s Rh(+) red blood cells may also reach the mother in small amounts and stimulate the production of anti-D antibodies in the mother with Rh(-) blood. If the mother-to-be is pregnant for the first time, the antibodies produced are large molecular amounts of IgM, which cannot cross the placenta and return to the baby; however, if the baby is still Rh(+) for the second time, the immune memory left by the first pregnancy is reawakened to produce large amounts of IgG antibodies, which, once produced in the mother, may cross the placenta and return to the baby. The combination of large amounts of anti-D antibodies and the D antigen of the baby’s red blood cells can trigger risks such as hemolytic disease of the fetus, fetal edema and even fetal death. What can pregnant women with Rh-negative blood type do to reduce the risk of hemolysis in their babies? For mothers with Rh(-) blood, it is generally recommended that: 1) 300 μg of anti-D immunoglobulin be given intramuscularly between 28 and 30 weeks; 2) an additional 300 μg be given intramuscularly within 72 hours after delivery of the fetus. If forgotten after delivery, additional injections within 13 days can still produce partial protection; 3. Immunotypic prophylaxis is recommended for all events that may cause anti-D antibodies in women with Rh(-) blood (maternal blood sensitization effect events), such as abortion, ectopic pregnancy, chorionic villus biopsy, amniotic fluid or cord blood puncture, tubal ligation, transfusion of Rh(+) blood and some obstetric operations. In addition, when a mother-to-be with Rh-negative blood type becomes pregnant again, she should go to the hospital to check if anti-D antibodies are already present in her body. If anti-D antibodies are already positive, immunoprophylaxis loses its meaning and the risk of fetal hemolysis becomes greater, and monitoring of the baby should be strengthened during pregnancy, and you should actively contact and consult your obstetrician for details.