Rh positive means Rh blood group positive. ABO blood group typing is the most common blood group classification, which includes type A, B, O, AB; another blood group typing system is rh typing system. In Asian countries, the number of Rh-positive people is much larger than the number of rh-negative people, and rh-negative blood, is a rare blood group. Distinguishing between rh-positive and rh-negative is helpful in preventing hemolysis in newborns. The rh negativity is determined by the presence or absence of D antigen on the red blood cell membrane, with D antigen being positive and no D antigen being negative. rh negative patients can only be transfused with rh negative blood, and rh positive people can be transfused with both rh positive and rh negative blood.