I'm a guy and agree with what Nikki said. When I was worried about my girlfriend being pregnant, my best friend was Google. While she was at work or asleep I'd be here at the trusty computer reading, then clicking links on those websites, then more links, etc. After about 3 weeks of doing this, I can actually talk to her about those kind of things and not be totally oblivious~
Oh, and in response to the lecture at hand - don't worry about it! Hell, if I worried about that, I might kill myself everytime my girlfriend brings her clothes to my laundromat to wash them. Just relax a little, in the past three months I've realized just how far worrying about things can get you - fuckin' nowhere
(except for the fact that I lost about 35 pounds and now don't really eat but once every other day!)