An individual either has, or does not have, the "Rh factor '' on the surface of their red blood cells. This term strictly refers only to the most immunogenic D antigen of the Rh blood group system, or the Rh − blood group system. The status is usually indicated by Rh positive (Rh+ does have the D antigen) or Rh negative (Rh − does not have the D antigen) suffix to the ABO blood type. However, other antigens of this blood group system are also clinically relevant. These antigens are listed separately (see below: Rh nomenclature). In contrast to the ABO blood group, immunization against Rh can generally only occur through blood transfusion or placental exposure during pregnancy in women.
where does the rh negative factor come from
does not have the D antigen