They don't go to orthopedic surgeons and ask for that kind of information. The more regulation, the more difficult things can be. For example, I was trained in Great Britain and the regulation there is that a you cannot transfer more than three embryos to the woman, to reduce the chance of multiples. But when you have somebody who is 42 and all the data shows that multiple pregnancy is low in that age group, if you transfer 5 or 6, you may boost her chances. If you were the physician, you would advise a procedure that gives her a better chance of success.
Rules are good, but rules that are too rigid ca jeopardize the chances of certain age groups.
Part of that is to tell them the chances that multiple pregnancy will occur. By the same token, you try to explore the religious and social background of the couple. If they understand everything and they are willing to take the risk, maybe you can transfer four embryos if the situation calls for that. If their religious background indicates they wouldn't even consider selective reduction, maybe you should transfer more three. You know at least the maximum is triplets.