Jaundice baby 4 days old?

Time. As long as the level continues to decrease I wouldn't worry about it. The lights will take care of the jaundice. This is due to an abundance of dead red blood cells and the liver not being mature enough at birth to remove the bilirubin correctly. My daughter was under the lights for 2 days and all went well. 2 of my others had slight jaundice but it wentaway without lights. Good luck.