Hemolytic disease of the new born is another name for erythroblastosis fetalis,this is due to blood group incompatibility between mother and fetus and this will lead to anaemia.if the anaemia (in utero) is severe the fetus will exhibit signs of hydrops fetalis (a condition which develops in utero due to chronic anaemia secondary to hemolytic diseases).kutokana na hemolysis level za unconjugated bilirubin will rise and may cross the blood brain barrier and lead to kernicterus