Methylprednisolone is classified by Hale's as an L2 medication - his scale runs from L1 (Safest) to L5 (Contraindicated). The AAP has classified it as a maternal medication usually compaitble with breastfeeding.
From Hale's: "the amount of methylprednisone and other steroids transferred into human milk is minimal as long as the dose does not exceed 80 mg per day. However, relating side effects of steroids administered via breastmilk and their maternal doeses is rather difficult and each situation should be evaluated individually."
I can scan the entry from Hale's in and send it to you as a .pdf if you would like - PM me with your email address if so. I would recommend checking with your doctor, showing them the Hale's entry, and seeing what they have to say. I am not a doctor and am not giving you medical advice, just passing along what is available in appropriate reference materials.
