 Breastmilk jaundice is caused by an increased concentration of β-glucuronidase in breast milk → ↑ deconjugation and reabsorption of bilirubin → persistence of physiologic jaundice with unconjugated hyperbilirubinemia.Onset of breastmilk jaundice is within 2 weeks after birth and lasts for 4–13 weeks.While most cases of newborn jaundice are not harmful, if bilirubin levels are very high, brain damage — kernicterus — may occur leading to significant disability.