Thanks for the input everyone. I found an OB who is also a triathlete who, I assume, will be able to speak more specifically about issues such as frequency/duration/intensity of workouts and rides, instead of just handing me the number 140 and sending me on my way. Another thing my current OB told me was absolutely NO running (why? I don't know..). I don't want to be too hopeful that this new OB will tell me everything I want to hear, but I think I can count on advice that will be more specific to my current level of fitness.
Also found a good book that I have already ordered: Exercising Through Your Pregnancy by James Clapp. It's highly recomeneded by women athletes who are or who have been pregnant, so it looks like I've managed to find some guidance.
Thanks, Vigg