ordered a bunch of these..  but the sizing was very strange.  very long and very narrow.  maybe my son is chunkier than most.  he is 7 months old and i am buying 12-18 mo for him.  but even at 7 mo old, these were skin tight around the body.  there is a little sign on them that says that they are supposed to be a tight fit for safety because they are not fireproof, but i think that is just something they stuck on there because they were made wrong.