According to the search results, the level of bilirubin that is harmful to newborns is around 20. If the bilirubin level becomes very high, it may affect some of the babys brain cells, causing the baby to be less active. In rare cases, a baby may develop a condition called kernicterus, which can cause cerebral palsy, deafness, or certain forms of brain damage. Therefore, it is important to monitor the bilirubin levels in newborns and seek treatment if necessary. The American Academy of Pediatrics uses a newborn jaundice level chart to determine if a baby needs treatment based on the total serum bilirubin level and age. If the bilirubin level is too high or rising too quickly, the baby may need treatment, which usually involves phototherapy or, in severe cases, an exchange transfusion. It is important to keep the baby well hydrated with breast milk or formula and encourage frequent bowel movements, which help to remove the bilirubin.