ABO blood group system letter O for "ohne", meaning without or zero; Landsteiner chose the latter.) This classification was adopted by the National Research Council and became variously known as the National Research Council classification, the International classification, and most popularly the "new" Landsteiner classification. The new system was gradually accepted and by the early 1950s, it was universally followed. The first practical use of blood typing in transfusion was by an American physician Reuben Ottenberg in 1907. And the large-scale application started during the First World War (1914-1915) when citric acid was developed as blood clot prevention. Felix Bernstein demonstrated the correct blood
Blood type pregnancy or occasionally a blood transfusion with D positive RBCs. Rh disease can develop in these cases. Rh negative blood types are much less common in Asian populations (0.3%) than they are in European populations (15%). The presence or absence of the Rh(D) antigen is signified by the + or − sign, so that, for example, the A− group is ABO type A and does not have the Rh (D) antigen. As with many other genetic traits, the distribution of ABO and Rh blood groups varies significantly between populations. 28 blood-group systems have been identified by the International Society for