Can levels of jaundice in new borns go up?

Yes, because if the babies liver has not kicked in yet and started removing the toxins in the blood then the toxins can build up and your baby can get worse and worse. Watch out for Lethargy. If left untreated Jaundice can cause mental retardation because it is poison to the brain. But it has to reach very high levels for that to happen. Most babies are born with Jaundice that is easily treated by exposing them to sunlight for a few minutes here and there throughout the day. Just be careful for sunburns. But the sunlight was not enough for my son and he had to be put under a special light at the hospital. He had unusually high levels of Bilirubin. So if you are concerned I would have it checked. Sometimes the liver takes longer to kick in.