Why can't the swab their cheeks and do a dna test?
It is simple and painless. It can also tell if you are a carrier of the disease or not, so if you and your husband/or father of your children to be PC, where to be tested, you would both have to be carriers in order to have a child with CF. If one of you is a carrier and one is not, your children may be carriers, but they would NOT have CF.
When my sisters got married and wanted kids they got tested for being carriers. One is a carrier and one is not. All it took was a swab of the cheek.