My GI sent me to a maternal fetal specialist to discuss just that in a "preconception consult" so that we could evaluate the pros and cons. We discussed Imuran (similar to 6mp) and she said that she feels comfortable with it and that it is better to remain healthy while pregnant than to flare. She also said that if we decide to go ahead and get pregnant she would have to follow the pregnancy closely with extra ultrasounds and genetic testing to assure that the baby is developing properly. I asked her if she felt it was not advisable to conceive under these circumstances and she said absolutely not. As long as I was healthy I should not allow the meds to deter me from getting pregnant. She did say though that breastfeeding was a probable no-no. Perhaps you should get a referral to a maternal fetal specialist to discuss these issues so that you can make an informed decision.