A condition in which red blood cells in a newborn's blood are harmed by a protein produced by the mother's immune system.

Hemolysis refers to breakdown of red blood cells. In hemolytic disease of the newborn, immune system proteins called antibodies from the mother attack a newborn's red blood cells. The attack begins while the baby is in the uterus. Hemolytic disease of the newborn happens if the pregnant person's blood isn't a match for the baby's blood.

A newborn with the condition might be swollen from a buildup of fluids in the body. The baby also might have anemia. The liver or spleen might be larger than expected. The baby's skin might be pale or yellow, which might be easier to see on a white skin person than on a Black or brown person. The whites of the eyes also might be yellow.

The baby may need to get blood from a donor.