I don't really worry about that...according to my doctors I should be worrying about it now! Can you believe that? I had a doc tell me at 18 that if I wanted kids I had better "get on it" Lovely advice.
I figure that fear that you might change your mind isn't really a good idea, because then if you really didn't want a baby and you have one, everyone will be unhappy. Plus, there's always adoption.