A newborn with erythroblastosis fetalis has anemia, caused by the destruction of red blood cells.

Erythroblastosis fetalis occurs when the mother's blood enters the infant's bloodstream. If the mother has a Rh-negative blood type, the mother's immune system attacks the red blood cells of the fetus: the infant's red blood cells are destroyed, resulting in anemia.

Symptoms include jaundice, a rash, and swelling of the abdomen, legs and arms. About 1 infant out of 1000 has erythroblastosis fetalis.