The babies I see with bad jaundice are usually those who have had a rough birth with a lot of molding of the head, and often just can't get the knack of nursing well. My personal belief is that they have a headache and sucking hurts. So the baby sleeps, and only nurses or tries to nurse every 4-5 hrs. Starts getting jaundiced. High bili causes lethargy.
Baby sleeps even more, or is weak nurser.
My thing is to make SURE the baby is nursing before leaves the hospital, and if that means she stays an extra day, so be it. If baby not nursing well, I make sure mom knows how to cup feed water. I see baby back on 3rd day for wt and to watch him nurse. I don't check bili, no matter how yellow, unless baby still not nursing well. I put them in the window from the beginning if baby not nursing well, because I know he will get jaundiced.