In 1939, two scientist discovered an unknown element in the blood of teh Rhesus monkey. Thus the name, Rh factor. The RH factor is the antigen or protein attached to the Red Blood Cell. Rh is the protein substance present in the cells of most people, capable of inducing intense antigenic reactions. It is present in 85% of caucasians with a slighty higher percentage among blacks and orientals.
Rh incompataibility exist only if the mother is Rh negative and the baby is Rh positive, and if during pregnancy some of the Rh positive blood of the baby finds its way through the placenta and into the bloodstream of the mothe