I suffer from rheumatoid arthritis. My doctor wants to put me on Methotrexate. He also mentioned it could cause a miscarriage at a very early stage but a lower dose may not have that potential. Do you have any information on this?
Answered by Dr. Bill Toffler, M.D., EPM Volunteer
Methotrexate in any dose may be problematic. While your doctor may be right that it might not cause an abortion at a lower dose—the dose used for rheumatoid arthritis (RA) is generally quite a bit less (~4-8mg/wk) than might be used to try to deliberately cause an abortion (~50-75mg)—there are no references/studies that will confirm such a hypothesis. Nor could they ever easily be done. Methotrexate is an anti-metabolite that clearly has a potentially detrimental (deforming &/or lethal) effect on a developing conceptus or fetus. In fact it is contraindicated in pregnancy.
There are alternative medications for individuals with RA which are likely to be less harmful should you conceive. For example, Hydroxychloroquine (which is sometimes used as an anti-malarial) can be considered for use even during pregnancy as it has a “C” rating (i.e., weigh risk/benefit). Another is Sulfasalazine—which is sometimes also used for ulcerative colitis—with a “B” rating (animal studies show no risk, but controlled human studies are unavailable). Others—which are newer agents and considered disease altering—(just like Methotrexate but without the teratogenic or lethal effects on a fetus) are Remicade, Enbrel, Humira, and Kineret, each of which also has a “B” rating.