Yes, we would terminate. I feel particularly strongly about this now that we have a child with cf. We did not know until after she was born. We love her dearly and it is heartbreaking to think about what lies for her ahead. I know some of you have mild cases, and that's great. But our daughter has two severe mutations, liver disease that will most likely require transplant in the future, and alpha-1 antitrypsin deficiency (so if she's lucky enough to make it into her 30's she can deal with congenital emphysema, oh yea!). So no, in our case having another child with cf would seem cruel and selfish. We were extraoridinarily lucky that our third child had neither. The stress of waiting for the CVS test results was overwhelming. Now we've taken permanent birth control measures to ensure we never get pregnant again.
I realize this is going to be an unpopular answer. It is, however, the answer that works for us. I respect the fact that many of you feel differently and would abort for no reason. I can't speak the same.