I don't have any experience with this drug, so I looked it up in my Mosby's Drug Reference. It is listed as a pregnancy Category C, stating the drug is excreted in breast milk, so avoid nursing. I'm not sure what that category means. Perhaps Shelly will know.
Other than that, Prograf has a ton of possible side effects and adverse reactions, but no more so than prednisone. I guess if your doctor is recommending it, it's your decision.
Hope this helps a bit,