Keeping mom's UC well controlled produces the best outcome for her child. We've had many moms take the medications you're prescribed and have healthy and happy babies. Here's a few articles from our resources section on it:
From conception to delivery: Managing the pregnant inflammatory bowel disease patient
www.ncbi.nlm.nih.gov/pmc/articles/PMC3974516/The Second European Evidenced-Based Consensus on Reproduction and Pregnancy in Inflammatory Bowel Disease
ecco-jcc.oxfordjournals.org/content/eccojc/9/2/107.full.pdf