My boyfriend and I haven't been so easy on the protection, we're definitely a lot like rabbits. I've heard a negative blood type and a positive blood type make it harder to conceive, while we're not actively trying, as often as a condom has slipped of or the pull out method failed, I'm getting a little concerned. I don't know either of our blood types nor are we ready for children, but the thought heavily ponders my mind. What are some things that affect fertility?