We did medicated IUIs (first clomid, then shots) because, although I cycled regularly (28-30 days on average), my eggs were not fully maturing (horomone issues). That was discovered because my doctor monitored my cycles and folicles unmedicated for a few cycles before deciding on a course of action. We did 5 (I think! That's kinda bad, that I can't remember!) IUI cycles. My gyn/infertility specialist is very familar with cf patients, and he monitored my folicles via ultrasound very, very, closely, to make sure that multiples (especially more than 2) were "doubtful", though, of course, still a very real possiblity.