There's risk in pretty much everything, ultimately depends whatever you feel is best. It's good to have a variety of options to consider though!
If it were me, I'd give the mesalamine a shot. Sulfasalazine is less then $80.00 a month if you had to pay 100% out-of-pocket (balsalazide disodium is perhaps $200 a month at 100% OOP). What you have is pretty minor and it might be enough to regain a remission. Not buying the "meds never do nothing" bit, as they always have an affect (it just may not have been enough of a difference to quell the flare on its onset). Now, is another matter entirely.
Azathioprine is certainly more of a concern then some of the other UC meds, as far as pregnancy risk goes (worse rated then the rest). However, we've had moms give birth to perfectly healthy and happy babies on all of the various meds, from mesalamine, to azathioprine, biologics, and sometimes all of the above simultaneously. So it does not produce a certainty of a bad outcome by anymeans (rather a small risk that must be weighed).
Keeping mom healthy during pregnancy and her UC under control produces the best outcome for the child (even when mom is on meds). As your UC flaring badly during pregnancy has its own risks, predominately early delivery of an underweight infant. Given right now, you're doing well and I hope you continue to do so. I would keep a cautious eye on your symptoms as flares can happen during pregnancy or postpartum (hormonal and all sorts of changes within the body during a pregnancy could have an affect in that outcome). We've had moms have uneventful pregnancies here, and others flare during or right afterwards. No knowing, as UC loves to be totally random and keep us guessing (much to our frustration and to add to our anxiety, unfortunately (o_O).
LDN would be a much bigger unknown is it really isn't studied in pregnancy in UC dosages, you'd be experimenting. LDN isn't without side effects and can impact the liver, as one example.
There's a couple good reads on what are the risks and odds, if you're so inclined.
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.pdfPost Edited (iPoop) : 6/19/2018 2:27:38 PM (GMT-6)