Jaundice is one of the most common symptoms in newborns, and a marked increase in unconjugated bilirubin can lead to bilirubin encephalopathy and sequelae, which are more likely to occur in premature infants and should be treated urgently. It is important to identify physiological jaundice or pathological jaundice. How to identify physiological jaundice in newborns? 1, physiological jaundice: mostly appear in the first 2-3 d after birth, peak in the 4th-6th d, serum total bilirubin ( TSB ) not 204μmol/L (12mg/dl) in term infants, not more than 256μmol/L (15mg/dl) in preterm infants, combined bilirubin not more than 34umol/L (2mg/dl), in term infants in 2 weeks after birth, in preterm infants in 3-4 weeks The bilirubin will subside in 2 weeks after birth for term infants and 3-4 weeks for preterm infants. The child is in good general condition and has a good appetite. Physiological jaundice is closely related to the characteristics of bilirubin metabolism in newborns. With the popularization of breastfeeding in recent years, the peak TSB of normal term infants is significantly higher than the traditional standard, reaching 256-290 μmol/L (15-17 mg/dl). For preterm infants, the concept of so-called “physiological jaundice” is no longer valuable, because preterm infants, especially very low birth weight infants, may develop bilirubin encephalopathy even if the TSB is in the normal range. 2, pathological jaundice: If jaundice appears within 24h after birth, the degree of jaundice exceeds the range of physiological jaundice, the daily TSB rise value > 85μmol/L (5mg/dl), jaundice remission time is delayed, combined with increased bilirubin, etc., should be regarded as pathological jaundice, while the child has the manifestation of the original disease.