It seems to me everyone is thinking about the rights of the baby, and weather or not it should be allowed to live having cf. You must keep in mind that if the parents are not able or willing to care for a sick little monkey hen it would be cruel to force it upon them and the child.
I am a husband of a pwcf and it has been very very hard to care for her over the last decade. There is not only the financial stresses but the emotional heartache of fighting a losing battle. My wife and I cannot have any children due to complications with cf, if we were able to and the baby tested positive for cf we would abort as well. I know personally I could not emotionally go through this pain again, I don't think I would be able to provide the care needed to ensure the survival of a pwcf, it's too draining on me. Maybe that's how your aunt feels, maybe she's not mentally able to cope with that diagnosis.
Before you people say that they should bring another sick child into this world, you should consider the people who would be doing all the work, it would be unfair to the child otherwise.
:(