M.F.
It depends on why he wants to do the test. I understand it's a fairly common gene among caucasians. If you and your husband are both carriers, it may increase your chances of having a child with CF, which might increase the risk of miscarriage (which can happen if a fetus has genetic problems) or complications at delivery. (I don't know this for sure, just guessing at why it's a standard test for couples undergoing in vitro). If it's easy to test for and it's not cost prohibitive, I don't see why it would hurt to know.