Jaundice is extremely common in babies, affecting around 50%-60% of full term newborns, and around 80% of premature babies born before 37 weeks. It's usually mild, resolving on its own within a couple of weeks. Mild jaundice is also called physiological jaundice. Jaundice is caused by a build-up of bilirubin, an orangish waste product left over when red blood cells break down. The liver is the organ that gets rid of bilirubin, but in newborns, their livers are often not working quickly enough to