Hemolytic Disease of the Newborn

Hemolytic disease of the newborn, also called hemolytic disease of the fetus and newborn or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus at or around birth, when IgG antibodies produced by the mother pass through the placenta and attack antigens on the red blood cells in the fetal circulation, breaking down and destroying the cells. The fetus can develop reticulocytosis and anemia, and the intensity of the disease ranges from mild to very severe, with fetal death from heart failure possible in severe cases. When the disease is moderate or severe, many erythroblasts appear in the fetal blood, which is why the more severe forms are called erythroblastosis fetalis.