M.G.
I was on Prednisone for the end of my pregnancy, so I'm not sure what it does when you're trying to get pregnant. Ask your doctor if she could refer your to others (or a forum) to find out who's been on prednisone for conception.
So my info probably doesn't help you too much, but for what it's woth:
Prednisone actually made me feel a little better, (I suffer from ITP during pregnancy...low platelets, spontaneous bruising etc, and I actually had immune gobulin infusions during pregnancy and an emergency blood transfusion immediately after delivery) but I certainly could do with out the side effects of prednisone! I gained about 15 pounds in a couple of weeks. And after I weaned off it, I had a problem with hair loss....like patchy bald spots (luckily way in the back). But it seems to give your body the help it needs in certain areas. Hopefully it works for you! Come back to Mama pedia and look up old posts of mine about hair loss after you ween off the drugs. I got a lot of great advice in that area.
Best wishes to you and lots of prayers!