many hold that a baby with jaundice cannot have the bris on time. My son developed jaundice within three days (so common in newborns), and our frum pediatrician spoke to the mohel and they both agreed the bris should be b’zman, and so it was. There were absolutely no ill effects. The extent of the jaundice, however, needs to be examined both visually and through blood tests, and if severe enough, the bris will be postponed.
If a baby seems to have a blood clotting problem at birth, that is a MAJOR reason to postpone, as would be any condition that is potentially life-threatening. My granddaughter was in the neonatal unit for two weeks. Had she been a boy, the bris would definitely not have taken place on time.