Babies body is having a hard time getting rid of toxins in the body which is why the skin is yellow. Normally if the doctor is worried about it they will have you come and put them under ultraviolet lights for a certain amount t of time or send you home with an ultraviolet light belt. Once the baby starts peeing and pooping well the levels should go down. Day 3 is the worst. Putting them in sunlight helps as well.
jaundice is the yellowing of their skin. my daughters pediatrician prescribed a vitamin d supplement to give her daily. but if you don't get prescribed a supplement, what you should do is put the baby in their crib or a bassinet by a window that has the shades open so the baby can get the vitamins they need from the sun. that helps take care of any jaundice issues.