I suffered with UP for twelve years prior to my surgery. My GI doctor had me on Colazal. He said the Asacol didn't reach the rectum. He most likely was correct, because, if anything, the Colazal did keep the ulcerations confined to the rectum. At the time of my surgery, last year, my colon was not bad at all but my rectum was still a mess.
I was 63 at time of surgery, so no pregnancy issues. However, I doubt it is a good idea to use rectal meds while pregnant. Only my personal thought but better to check with your OB/GYN. The best of luck to you. God bless.