Final answer:
Rh antibodies target antigenic determinants on red blood cells (RBCs). The most critical Rh antigen is the Rh D antigen. These antibodies are significant in the context of pregnancies and can lead to complications like hemolytic disease of the newborn if an Rh- mother produces anti-Rh antibodies against her Rh+ fetus.
Step-by-step explanation:
Rh antibodies are primarily directed towards antigenic determinants that are present on red blood cells (RBCs). The Rh factor, particularly the Rh D antigen, plays a significant role in blood transfusions and pregnancies, as these antigens are proteins found on the surface of RBCs. Individuals who lack the Rh D antigen are considered Rh negative (Rh-) and those who possess it are Rh positive (Rh+). During pregnancy, an Rh- mother carrying an Rh+ fetus can produce anti-Rh antibodies which can lead to complications such as hemolytic disease of the newborn in subsequent pregnancies if untreated with prophylactic interventions like RhoGAM.