Outcome of first-trimester exposure to low-dose methotrexate in eight patients with rheumatic disease

Methotrexate (MTX), when used to treat malignancy or psoriasis, has been implicated in anecdotal reports as a teratogen or abortifacient in the first trimester of pregnancy. We are unaware of any previous reports that describe the course of gestation and the effect on subsequent offspring in patients treated with low-dose oral MTX for rheumatoid arthritis, and therefore present our experience.

We report on eight women experiencing 10 pregnancies. Mean number of weeks of gestation while taking MTX was 7.5 (range 2 to 20 weeks). Outcome of pregnancies included five full-term babies (FTB), three spontaneous abortions (SAB), and two elective abortions.

There were no significant differences in either the FTB or SAB group when considering risk factors including smoking, alcohol, concomitant medications, and age. One of three in the SAB group had recurrent abortions prior to MTX therapy. All five of the FTB group had uncomplicated pregnancies and deliveries. All offspring were of normal height and weight at birth with no physical abnormalities. All children reached growth, development, and intellectual stages normally, and their present mean age is 11.5 years. No observed learning disabilities or medical abnormalities have occurred in any of these children.

In this uncontrolled study we failed to demonstrate tertogenicity of MTX. However, the possibility of abortion due to MTX use remains.