Thanks everyone for your advice it is much appreciated! Funny how everyone's Dr seems to have difference feelings about the Imuran / Prednisone issue.
My GP called me this morning and he has spoken with my OB (who i am yet to see in person since becoming pregnant, have an appointment in a few weeks time) and he said he has had some patients on Imuran throughout pregnancy but would prefer if i could cope with the Prednisone instead. I know in the past my Crohn's has responded well to the Prednisone so i am inclined to "tough it out" but i did tell my GP that i though 25mg daily was a failry aggresive amount to start me on. He said he would let me trial just half a tablet a day (so round about 12.5mg) to start with and if that wasn't working he would have to bump it back up again. He has also made an appointment for me to see a Gastro in a few weeks time to get his advise. (The problem with living in a regional area is that we don't have a permanant Gasto in town, they only visit for 2 days a month. And unfortunatley they only seem to last about 6-12 months then a new one starts coming. Very Frustating have to retell your medical history for the last 14 year to someone new all the time!)
Anyway, that makes me fell a little bit better, just taking the smaller dosage to start with. Its not that i don't want to get it under control as quickly as possible, i just don't think i need to go in all guns blazing. I still have a long road ahead of me yet!

I will know more after my scan on Wednesday and my GP appointment on Friday.