Newborns often develop yellow skin 2-3 days after birth, mostly on the face and neck, and in severe cases the sclera, trunk, and limb skin is also yellow. Children generally have no other discomfort, and their spirit, milk intake and bowel movements are normal. In preterm infants, jaundice is slightly more severe than in full-term infants, and jaundice can be delayed for 2 to 4 weeks. This is what is known medically as physiological jaundice. No special treatment is needed. However, if the jaundice in newborns appears too early, too deep, late or recede but reappears, it should be highly noted and needs to be determined whether there is infantile hepatitis syndrome.