Rh factor science definition

Any of several antigens present on the surface of red blood cells in most humans. People with Rh factors are classified as having a blood type that is Rh positive, while people who lack the antigen are said to be Rh negative and can produce powerful antibodies that destroy red blood cells if given a blood transfusion from an Rh-positive donor. A woman who is Rh negative and is pregnant with an Rh-positive fetus can produce antibodies that are life threatening to the fetus. See Note at blood type.