I have heard that sweat tests in young babies are not that realiable and that some babies are then sweat tested again at a later date to get a more accurate one. But nowadays that they have the genetic testing available, if the genetic testing comes back positive (two mutations) then there is really no need for another sweat test.Sweat testing used to be the "gold standard" when that is all they had and it is still a useful diagnostic tool when the test results are very clearly positive. But there are many kids that test normal or borderline on the sweat that then go on to have the genetic test and show positive on that.If the CF clinic is telling you that your child has CF, then I would believe them or get a second opinion if you don't trust them. If you are just relying on a Pediatrician for the diagnosis, then get to a CF Center right away, so you can get started on treatments for your baby.