What is the birth injury kernicterus (brain injury) from hyperbilirubinemia - jaundice?

As a body breaks down old red blood cells, it creates a yellow pigment called bilirubin that is processed by the liver prior to excretion. Some newborns have underdeveloped livers that cannot process this waste efficiently. If there is a delay or disruption in this process, bilirubin that builds up in the body may begin to collect in brain tissue and cause serious and permanent brain damage (bilirubin encephalopathy).