I can't remember who asked me this question, but I now have the answer....
I just got back from my high-risk OB appt and they have switched me to Heparin (Low-Molecular Weight, I believe) because it IS reversible should I go into labor unexpectadly, whereas Lovenox is not. I can't remember the reversal med, but it exists so that should I require an emergency c-section, they would give me this shot and send me on my way.