Neonatal jaundice, also known as neonatal hyperbilirubinemia, is a common clinical problem of the neonatal period, caused by the accumulation of bilirubin in the body, resulting in symptoms of yellowing of body organs or skin. The range of neonatal jaundice medically refers to the range of serum bilirubin in newborns, which is usually visible to the naked eye when it exceeds 5-7 mg/dl. Usually jaundice can appear within 2-3 days in newborns born at full term, with a peak at 4-5 days, and can subside in 5-7 days, existing usually for no more than 2 weeks. If jaundice is present in preterm infants, the jaundice may appear on days 3-5, peak on days 5-7, and subside around days 7-9, usually lasting 3-4 weeks. Clinically, full-term newborns are usually tested for bilirubin values within 7 days to form a table that will help determine whether the jaundice is normal physiological or pathological and to determine whether treatment is needed. In general, a daily rise in serum bilirubin of <5 mg/dl or <0.5 mg/dl per hour is considered normal. However, this classification of test values is not absolute because there are many factors that influence the appearance of elevated bilirubin values in newborns, and the cause of neonatal jaundice should be analyzed in conjunction with a variety of factors. In addition to the value of serum bilirubin, the normalcy can be determined by the clinical manifestations of jaundice. If the newborn is generally well, without obvious crying and painful manifestations is usually physiological jaundice. If the child has a high serum bilirubin value and the jaundice does not subside on its own for a long time, you should communicate with your doctor, assess the risk of jaundice during the consultation, and actively take relevant treatment, etc.