There are so many factors that can interfere with the pill, patch and shot such as antibiotics (especially antibiotics)...if you girls are smart it's no glove no love time. What I told my sons was this...
I don't care what she takes or how many times she says it's safe, you can't wear too many. Sex is great but out of wedlock babies are a mess from the get go. It's the 21st century, there is no excuse for getting knocked up "accidently".