"Jaundice is a condition in which the skin has a yellowish color. This happens when an excess amount of a chemical called bilirubin is in the blood. Jaundice is more common in babies who are breastfed, particularly babies who are having difficulty nursing. Jaundice is also more common in babies who are premature. Most newborns have some jaundice, often called “physiological” or “normal” jaundice, in the first week or so after birth. In breastfed babies, jaundice often lasts for 3 weeks or more. In formula-fed babies, most jaundice goes away by 2 weeks. If you are breastfeeding, you should nurse your baby at least 8 to 12 times a day for the first few days. This will produce enough milk to keep your baby hydrated and help keep the bilirubin level low."
More answers about jaundice in "Common Questions About Neonatal Jaundice" from JAMA Pediatrics.