You could give it a whirl I guess. The folks that I know who have many (5+) kids are religious jews, catholics, muslims and mormons. I don't know if all of these people have defered sex till marriage but they are certainly not the ones racking up tripple or even double digit bodycounts. Are you saying you have a line of reasoning that people who maintain religious adherence today are doing it so they can have unrestrained sex?
Catholicism has been in general against contraception.
Of course it's still used, but probably at lower rates.
Non protected sex leads to pregnancy at a much higher rate than protected one.
I expect it to be similar for other similar religions.
Bodycount is also irrelevant, the total numer of intercourses is what matters. I'm not sure if having a stable partner since a young age leads to more total intercourses than occasional partners, but I'd be lead to thing so.
I cannot properly put into words how different the reality you live in must be different from the one I do.