Why is RH-positive type A blood called "noble blood"?

There is no such thing as calling RH-positive type A blood "noble blood." RH-positive type A is actually a relatively common blood type. The detailed analysis is as follows:

Clinically, according to human blood group systems, there are various classification methods. Using the ABO blood group system, blood types can be categorized into type A, type AB, type B, etc. When classifying according to the Rh blood group system, blood can also be divided into Rh-positive and Rh-negative. Among these, individuals with Rh-positive type A blood are numerous, making this blood type quite common. Therefore, there is no basis for referring to Rh-positive type A blood as "noble blood."

Usually, before a blood transfusion, an ABO blood typing and cross-matching test must be performed, along with Rh blood typing and compatibility testing. For women during pregnancy, if the mother has Rh-negative blood while the fetus has Rh-positive blood, in cases of infection or trauma, fetal blood may enter the maternal circulation. This can trigger the production of specific antibodies in the mother against the fetal red blood cells, leading to a severe antigen-antibody reaction. This reaction can destroy red blood cells and potentially cause hemolytic disease in the fetus, affecting normal fetal development.