Hi Millerkat1 - Congratulations on your pregnancy, but sorry for your recent diagnosis. In my opinion, being in a flare during pregnancy is more dangerous than most drugs used to treat Crohn's Disease. My main objective at this point would be to get out of the flare. Prednisone and Pentasa are usually deemed safe for use during pregnancy. The Pentasa is not likely to get you into remission, but a taper of Prednisone may and then the Pentasa can keep you in remission.
How far along are you in your pregnancy? It is also possible that you may go into remission on your own while pregnant, as pregnancy tends to naturally lower your immune system.
I was on Humira throughout my pregnancy and delivered a 10 pound healthy baby boy naturally. I felt great throughout my pregnancy but flared afterwards. Good luck with everything. I think it is most important to keep in constant contact with your GI and OB, they will help you make these difficult decisions.