The cause of breastmilk jaundice is not yet completely clear. Currently, studies consider that it may be related to the enzymes or genes in breastmilk, and there are two main theories: the theory of increased bilirubin enterohepatic circulation and the genetic theory. 1. The theory of increased bilirubin enterohepatic circulation: breast milk jaundice is related to the high level of β-glucuronidase in breast milk, which can break down the bilirubin-glucuronide chain and increase the amount of unconjugated bilirubin in the intestinal tract, which increases the burden on the liver and leads to the occurrence of jaundice. 2. Genetic theory: Another study suggests that breast milk jaundice is associated with alterations in the liver glucuronosyltransferase-related genes, which can lead to hereditary high-risk conjugated bilirubinemia. Breastmilk jaundice usually subsides after 72 hours of breastmilk suspension. If the symptoms are more serious, it is recommended to consult a doctor and take relevant therapeutic measures under the guidance of a physician.