Most Common Form: ABO Incompatibility

     ABO incompatibility is the most common form of Erythroblastosis fetalis found.  This happens if the fetus has blood type A and/or B while the mother's is type O.  Antigens found on the blood cells trigger the immune system to produce antibodies to fight a foreign blood type if different blood types come into contact with each other.  The blood of a fetus and that of the mother's usually do not come into contact, but there can be instances where they do, as in times of birth.  With ABO incompatibility, the mother's antibodies produced by the blood cells' antigens will try and expel the foreign blood type of the fetus' out of the mother's body.
     These antibodies of the mother that pass across the placental membrane could enter the newborn's bloodstream and result in the destruction of some red blood cells.  This process produces more bilirubin within the newborn and which in turn could lead to newborn jaundice.

-Teresa