The external manifestation of jaundice is yellowing of the skin and is one of the most common symptoms in newborns. Most newborns will show jaundice after birth, some of which are physiological and can be observed, while others are pathological and require treatment. Especially in premature babies or newborns with small days, if jaundice is obvious and not treated in time, it may lead to nuclear jaundice, resulting in sequelae. The main causes of physiological jaundice: (1) To survive, the fetus needs a large number of red blood cells in the blood to transport enough oxygen from the mother; after birth, the respiratory system begins to work and the oxygen supply is sufficient, so that too many red blood cells are no longer needed to transport oxygen, resulting in increased destruction of red blood cells and excessive bilirubin production. (2) The metabolic function of the liver of newborns is not yet perfect, and the normal intestinal flora has not yet been established, which cannot further transform bilirubin and excrete it out of the body. As a result, excess bilirubin accumulates in the blood, and when it exceeds a certain amount, it stains the skin, mucous membranes and the whites of the eyes yellow. There are many causes of pathological jaundice, common ones such as infection, hemolysis, breastfeeding, etc., and rare ones such as biliary atresia, genetic metabolic diseases, intrauterine viral infections, biliary mucus syndrome, congenital intrahepatic bile duct dysplasia, etc.