Pregnant or not, it makes sense when you have ulcerative colitis to avoid greasy, fried, high-sugar, and spicy foods. Stay away from nuts, popcorn, and corn, because they can make swelling worse.
Make sure you drink plenty of water, since diarrhea can cause dehydration.
Sometimes, five or six small meals a day are easier to handle than three big ones. This habit also helps when you get nausea and heartburn because of your pregnancy.