Irregular antibodies are blood group antibodies other than anti-A and anti-B. They are more common in pre-transfusion testing, neonatal hemolysis testing or pregnancy testing. Irregular antibodies negative means that there is no hemolysis in the patient’s body, and the chance of hemolysis in newborns is small, and is a normal indicator. 1. Pre-transfusion testing: Irregular antibodies do not exist in normal human serum, and pre-transfusion testing helps to select blood that does not contain the corresponding antigen against an antibody, so as to avoid hemolytic transfusion reactions due to the destruction of the patient’s red blood cells caused by the input of irregular antibodies; 2. Neonatal hemolysis Detection: detection of irregular antibodies in the child has a more important role in determining the presence of neonatal hemolysis, if it is negative, it usually means that there is no neonatal hemolysis; 3. Pregnancy test: for pregnant women who have a history of blood transfusion, pregnancy or need multiple blood transfusions in a short period of time, serum irregular antibody screening can detect irregular antibodies as early as possible to reduce the probability of neonatal hemolysis. Usually, if the pregnancy test is negative for irregular antibodies, the chances of neonatal hemolysis in the newborn and the possibility of hemorrhage during maternal delivery are smaller.