Pretty much every criminal says they've learned more crime/techniques and could build their "network" in prison. So more prisoners would likely have effect of continuing/promoting crime.

Anyway - no birth control method (except abstaining) is 100%, even when you stack multiple different ways it can happen.

And some methods of birth control - like pill for woman and vasectomy for guys - can mess you up long term.

Women describe getting off the pill like completely changing their taste/smell senses, even brain/thinking ...etc (which sounds similar to what happens in/after pregnancy). When they give it to teenage girls (to "fix" their irregular cycle) they often gain weight..

And while vasectomy could be reversed, it's not guaranteed it would work.