Rh Antigen (D Antigen)

In addition to the ABO blood group system, blood is also classified based on the Rh factor. The Rh factor refers to the presence or absence of the D antigen, a protein found on the surface of red blood cells.

If the D antigen is present, a person is Rh positive (Rh+). If the antigen is absent, the person is Rh negative (Rh−). The Rh factor is genetically inherited and plays an important role in blood transfusions and pregnancy.

Rh Incompatibility

Rh incompatibility can occur when Rh-negative individuals are exposed to Rh-positive blood. When this happens, the immune system may recognize the Rh antigen as foreign and produce anti-Rh antibodies.

This situation is particularly important during pregnancy. If an Rh-negative mother carries an Rh-positive fetus, the mother’s immune system may produce antibodies that attack the fetus’s red blood cells. This condition is known as hemolytic disease of the newborn and can lead to serious complications if not treated.

Modern medical treatments, including Rh immunoglobulin injections, help prevent this immune response and protect the developing fetus.