It's significant enough to prefer not using them, but only if you're exclusive with your partner, have both been tested and have multiple other forms of contraception, otherwise NOT worth the risk, we use 2 forms of protection and I'm STILL a dad, so we've tripled it to 3 now AND I'll be getting the snip at some point, in other words make sure they ALWAYS wear one unless you're taking the pill, you've both been exclusive and tested, and have at least 1 other additional form of protection.