Erythroblastosis neonatorum is a medical condition that occurs when a mother's blood type is incompatible with her newborn's blood, causing the destruction of red blood cells in the baby's body. Synonyms for erythroblastosis neonatorum include Hemolytic Disease of the Newborn, ABO incompatibility, Rh incompatibility, fetal hemolytic disease, and neonatal jaundice. Hemolytic Disease of the Newborn (HDN) is the most commonly used term as it naturally encompasses all causes of the disease. ABO and Rh incompatibilities are specific causes of HDN based on the mother and baby's blood types. Fetal hemolytic disease is a more specific term for HDN caused by Rh incompatibility. Neonatal jaundice refers to the yellowing of the skin and eyes that occurs due to the buildup of bilirubin caused by HDN.