Are jumpers bad for babies?
I don't think they're "bad" unless they aren't used properly. Everything I own for Charlie has a diagram for how he should be sitting/standing in it for it to work the way it's intended for. For example, his jumper has a little pictures on it that shows how his feet should be touching the ground. He didn't use the jumper until his feet looked exactly like that picture. I also put a blanket in there with him to make sure he's not flopping over or anything.