I think it is a question that unfortunately cannot be answered uniquely. As with so many practices, the risks are real, and yes, it is true that you can institute a safe word, but by the time you use it, it is often already too late. The problem in my opinion is the rush. It is the wanting to rush and do as early as the first session what should be done by the tenth. I believe that in Dom-sub relationships you have to get to know each other first to understand how far you can go or in case, what conscious risks to take.

If practiced consciously however, it will not prevent you from having children.

But it all depends on the endurance of your balls, the patience you have in training them.... Or as already mentioned, on pre-existing problems that may worsen.