APA Dictionary of Psychology

an antigen-antibody reaction that occurs when blood from an Rh-positive individual is mixed with blood from an Rh-negative individual (see Rh factor) during transfusion or pregnancy. In pregnancy, this arises if an Rh-negative mother bears a child that has inherited Rh-positive blood: The fetal Rh antigens pass through the placental membrane, and maternal antibodies react through the placenta to destroy the fetal red blood cells. The damaged blood cells yield bilirubin, which a fetus cannot detoxify, and kernicterus may result. Also called Rh reaction.