Neonatal jaundice is a common disease in newborns, and most newborns will develop jaundice, but which cases can parents feel comfortable observing at home, and which cases must be seen by a doctor as soon as possible? First of all, neonatal jaundice is divided into physiological jaundice and pathological jaundice, physiological jaundice is almost all newborns will appear, so parents do not need to worry, just closely observe the child’s skin yellowing changes can be. Generally, full-term newborns begin to show skin yellowing 2-3 days after birth, and the peak of skin yellowing is 4-5 days after birth, which begins to subside significantly 5-7 days after birth and completely recedes 2 weeks after birth, while for preterm infants, it usually begins to appear 3-5 days after birth, reaches its peak 5-7 days, begins to subside 7-9 days after birth, and completely recedes 4 weeks after birth. In addition, the bilirubin level should not exceed 12.9 mg/dl in full-term infants and 15 mg/dl in preterm infants, while the bilirubin level increases more slowly each day, not exceeding 5 mg/dl. All of the above are physiological jaundice, parents do not need to worry, nor do they need special treatment, just observe at home. In contrast, if the child has pathological jaundice, it is important to seek medical attention as soon as possible, because if pathological jaundice is not treated in a timely manner, it may lead to irreversible brain damage, i.e., bilirubin encephalopathy, and once bilirubin encephalopathy occurs, the child will have a high mortality rate, and even if he or she survives, there may be neurological sequelae. Therefore, timely recognition of pathological jaundice and active treatment are of great importance to the child. If one or more of the following conditions are met, the child is considered to have pathological jaundice: 1) yellow skin staining visible to the naked eye within 24 hours after birth; 2) marked yellow skin staining, with bilirubin levels above 12.9 mg/dl in term infants and above 15 mg/dl in preterm infants; 3) rapid aggravation of yellow skin staining, with daily bilirubin levels rising more than 5 mg/dl; 4) delayed remission of yellow skin staining, i.e. Full-term infants still have skin yellow staining after 2 weeks after birth, and preterm infants still have skin yellow staining after 4 weeks after birth, when the bilirubin level should be greater than 5mg/dl; 5.Elevated conjugated bilirubin level, greater than 2m/dl; 6.After the skin yellow staining has reduced or subsided, it reappears again. If your child meets any one or more of the above six conditions, you should go to the hospital as soon as possible and ask your doctor to examine your child to clarify the cause of pathological jaundice so that it can be treated as soon as possible. The common causes of pathological jaundice in newborns are the following: infection, hemolysis, perinatal hypoxia, cephalohematoma, hepatobiliary disease, breastfeeding, etc. The causes of jaundice must be removed in order to cure the jaundice completely. If the predisposing factors causing jaundice persist, then treatment modalities such as light will not completely subside the jaundice. Physiological jaundice in newborns does not require treatment, while pathological jaundice requires treatment, which is mainly divided into symptomatic and causative treatment. Allopathic treatment means removing the cause of jaundice, such as symptomatic anti-infection treatment for children with infections, while for breastfeeding jaundice, breastfeeding must be stopped in order for the jaundice to subside. The symptomatic treatment mainly refers to blue light irradiation treatment. Blue light irradiation treatment has been used for more than 50 years at home and abroad, and its safety and effectiveness are recognized both at home and abroad as the first and best way to reduce jaundice. However, blue light irradiation can only temporarily reduce the jaundice, but if the cause of jaundice is not removed, once the blue light irradiation is stopped, the jaundice will worsen again. Of course, many parents are also concerned about the effects of blue light treatment on their children. The side effects of blue light irradiation mainly include fever, diarrhea, rash, bronchitis, etc. These complications are reversible, i.e. they will subside soon after the blue light irradiation is stopped and will not cause irreversible effects on the child, and the doctor is aware of the side effects and will usually take intermittent light and increase the amount of fluids to avoid these side effects. In addition, when blue light treatment is performed, the doctor will also use diapers and special materials such as eye shields to shield the child’s eyes and external genitalia to avoid the blue light to the retina and other effects. To date, no complications have been found in children growing up as a result of blue light irradiation, and the possible side effects of blue light irradiation are much less than those of bilirubin encephalopathy and are reversible.