Just to clarify........
There was a very good way to control it, actually. Responsible reproductive endocrinologists and potential parents do it every month. When you find you have too many follicles maturing and the risk of conceiving higher order multiples is obvious, you do not have sex/proceed with IUI. You stop the procedure in its tracks. In a case where a woman has previously conceived and given birth to twins, she clearly has a track record of success. It doesn't take a rocket scientist to see that if she has oodles of follicles getting ready to ripen into eggs, and sperm hits those eggies, there is a very good chance she will conceive higher order multiples.
Many REs will flat out refuse to go any further if they see too many follicles maturing and won't give the necessary medication to continue the process. You can certainly doctor shop and find one who will go along, because believe me, plenty of them are of the philosophy, "You can just reduce the pregnancy." Of course, that assumes the woman will be willing to reduce and not insist on carrying all the babies. But many woman won't do that.
It all comes down to what risks you're willing to take. Are you willing to risk conceiving 6 babies and trying to carry them long enough so that they will live and maybe even be healthy? If you're not, then you stop before insemination.
We had to make this decison with IVF as well. The first clinic we visited insisted on implanting 6 embryos on the first attempt. When I balked at that and said I didn't want to risk higher order multiples, they casually said I could reduce if that happened. To me, that was not a casual thing. So we found a clinic that was willing to be more conservative, implant fewer embryos and worry less about its precious statistics and more about its patients.
That being said, this is the same clinic that "produced" either septuplets or octuplets.

The inside scoop on that was that the mom hyperovulated (that was a whole other story on its own) and the doctors told her to stay a mile away from any sperm because she was bound to conceive higher order multiples. Clearly, she did not stay away from Mr. Sperm.

My dr. couldn't say all he wanted, but I could tell he was mortified that the entire country thought he had been behind the conception of those babies and planned it, when all along he'd tried to get her to avoid it. But it wasn't like he could go on national TV and say, "I told her not to have sex, but she did it anyway. There's no way I'd help a woman have 7-8 babies! I swear!"
That couple put on the "poor us" act too and begged shamelessly for whatever they could get. I don't have a lot of sympathy because they got themselves in this mess. On the other hand, DH & I took the responsible route and avoided higher order multiples.....Which meant we wound up spending tens of thousands of dollars more than the "gamblers" and never had a biological child, but we simply felt it was too irresponsible and unfair to any potential babies to take such chances. (Not to mention my health.) Most women who take such a gamble and conceive HOM lose big time. Kate beat the odds. But no one owes her or her kids a thing. Certainly not Pennsylvania.