I'm using wiki as a source here which may be a bad idea, but it says in America more women get their tubes tied than men get snipped, which really shocked me. It also says many women get their tubes tied at the same time as giving birth because it's convenient to do it at that time.
This is because when women have c-sections, sterility is always offered since they are "in there" already. And Wiki is always a bad choice for facts.
You could always freeze a few DNA samples in case you two change your mind or something tragic happens like divorce or death. I would wait until you were married at least 2 years though. Our "never" has been turning into "maybe" lately.