I didn't find out with the heel prick test (found out antenatally), but my son has CF and my friend just recently found out her wee boy had CF too (heel prick). Flick me a PM if she wants to email me or anything as I have HEAPS of info I could pass on, but sometimes too much info is not what you want!
By all accounts my wee boy is a happy boy, but we have had a few ups and downs, but its not the end of the world. He is normal in all other respects and I wouldn't change a thing for the world.