Essential facts Jaundice is one of the most common conditions affecting newborn babies. It is estimated that 6 out of every 10 babies develop jaundice, with even higher rates for premature babies. Caused by increased levels of bilirubin in the blood, jaundice is generally harmless, and resolves without treatment by 2 weeks of age. However, high levels of bilirubin can be harmful if not treated and need to be identified quickly.