I'm sure someone will come along with first hand experience, but from what I've researched about having my own baby...
Your GI is on the right track according to the docs here as far as drugs like Imuran remaining in your system for a long time. That being said, I also know that there are mothers of perfectly healthy babies who remained on their dose of Imuran throughout pregnancy and breastfeeding. The overwhelming philosophy here in the states (although not everywhere) is that "what is good for mom is good for baby". If you need Imuran to keep you healthy during your pregnancy, that's what's important. If you go off of it and flare, you would not be receiving adequate nutrition for your growing baby. As I said, I'm sure an Imuran-Mommy will be along soon to reassure you of that side of things. Obviously it is a very hard choice to make and one that involves YOU doing what you feel is best for you, and for your baby long term.
I was told by my midwife and an OB that my crohn's did NOT make me a high-risk pregnancy in and of itself, regardless of past surgeries. I was told that the risks would be about equal whether I decided on a vaginal delivery or a c-section. With a vaginal delivery, I increased my chances of injuring the area including my colon or possible tears/fistulas, etc. Basically, with my history of abscesses and fistulas I would run the risk of creating or irritating a complication in that area. If I went with a C-section, I was told that my vaginal and colon muscles and area would be safe, but that I might have a higher sensitivity to scar tissue or other complications because of the abdominal incision. I STILL have not decided which seems like the better option.
I hope that helps... or at least that it tides you over until the mommies arrive to answer you more specifically.
~best of luck to you.
27f, dx'd CD July '05 after 6 fistula/abscess surgeries
(miscarried at 13 weeks, now waiting to heal before trying again)
Stopped Humira August 22nd, 2008.
Went Gluten-Free, noticing some definite improvement.
Started LDN October 27th, and already LOVING IT.
"Our greatest fear is not that we are inadequate, but that we are powerful beyond measure."