I'm 16 weeks pregnant and am on prednisone and heart med. I went off imuran when I found out I was pregnant. I don't even know how much it was helping me because i was still sick with CD every day.
The biggest thing I find that helps while pregnant (and in general) is to watch what you eat: no sugar, limited or no processed foods, sourdough bread (easier to tolerate), nothing that can cause obstruction like steak.
I mostly eat a very natural homecooked diet and along with probiotics, it probably does the most for my crohns. Chicken, fish, well cooked veggies, fruits, honey-sweetened homemade goods, etc. When I stray from this sort of diet, I feel worse.
Most doctors say that if you get pregnant and are in remission, you will likely stay in remission while pregnant, but you might consider adjusting your meds to the most safest for the baby. My GI and other docs have told me that prednisone is the safest drug to use for CD while pregnant.