The midwife at our birth classes told us they were fine as long as bubba doesn't spend all day in there that's when they can get problems with their hips and also their feet because they use the tips of their toes to bounce so can cause problems with getting them to flatten their feet out. I think its like all things just use it in moderation, Nath has a Jumperoo and he loves it he has a little bit of reflux so its great for him to go in there after a feed to keep him upright of half an hour or so after his feed