RhD positivity is mainly an indicator in blood group testing. Human blood groups mainly include ABO blood group and Rh blood group, which are commonly found in ABO blood groups such as A, B, O, and AB. The presence of blood group antigens on the surface of human red blood cells, called Rh antigens, actually reflects a class of antigens on the surface of red blood cells, i.e. blood group antigens. Blood group antigen contains five types of antigens, among which D antigen is the most common and belongs to the most important type of antigens. Usually, in addition to ABO blood group, Rh blood group is also tested, i.e. D antigen in Rh blood group is detected. If the mother’s blood type is Rh negative, the father’s blood type is Rh positive, and the newborn is Rh positive, neonatal hemolysis may occur after birth. a positive RhD test mainly refers to a positive D antigen in the Rh blood type, so RhD is only a blood group marker.