How long it takes for neonatal jaundice to clear up is related to whether or not the baby is full term. Whether full-term babies or premature babies, most of them will have physiological jaundice after birth, which is normal. The baby is in a state of relative hypoxia in the womb, and the organism will maintain normal growth by increasing the number of red blood cells to carry enough oxygen. After the child is born, it can get enough oxygen by breathing, so the excess red blood cells in the organism will be destroyed. The destruction of red blood cells will release bilirubin, which will cause neonatal jaundice. For full-term newborns, jaundice usually subsides within 2 weeks after birth, while in preterm infants, jaundice appears and subsides a little later than in full-term infants, usually within 3-4 weeks after birth. Jaundice in newborns should be taken seriously and treated with blue light irradiation under the guidance of a medical professional if necessary.