Ever wondered why some people’s blood groups are positive and others negative? It’s all got to do with the Rh factor on your blood cells. Rh factor, or the Rhesus factor, is an antigen. You may or may not have this factor in your blood. When present, it is found on the surface of red blood cells and you are considered to have Rh-positive (Rh+) blood type. If you have no Rh antigen then you are considered to have Rh-negative (Rh-) blood type. The symbols are suffixed to your ABO blood type.
Rh factor plays a role in blood transfusion and haemolytic disease of the newborn (erythroblastosis foetalis). Transfusion of Rh+ blood to a person with Rh- blood type can cause a transfusion reaction. The Rh antibody in the person’s blood will destroy the Rh+ red cells of the donor blood. When an Rh-negative mother carries an Rh-positive baby, the mother’s body might react to the child’s Rh antigen. This Rh incompatibility can lead to haemolytic disease in the baby which is a severe condition of breakdown of the red blood cells.