<P> 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 . </P>
<P> 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 . </P>
where does the rh negative factor come from
where does the rh negative factor come from
does not have the D antigen
does not have the D antigen