Kernicterus is amage to the brain centers of infants caused by increased levels of unconjugated-indirect bilirubin which is free (not bound to albumin). This may be due to several underlying pathologic processes. Newborn babies are often polycythemic, meaning they have too many red blood cells. When they break down the cells, one of the byproducts is bilirubin, which circulates in the blood and causes jaundice. Alternately, Rh incompatibility between mother and fetus may cause hemolysis of fetal red blood cells, thereby releasing unconjugated bilirubin into the fetal blood. Since the fetal blood brain barrier is not fully formed, some of this released bilirubin enters the brain and interferes with normal neuronal development. Kernicterus may also be found in infants as a symptom of Crigler-Najjar syndrome type I, a hereditary hyperbilirubinemia that is fatal within 18 months of life.