Methotrexate is a potent drug that induces abortion at high doses, and is used at low doses to treat conditions like rheumatoid arthritis. There has been concern that women taking low-dose methotrexate and don’t realize they’ve become pregnant could have babies with birth defects.

Now comes word from French researchers that the risk does not seem to be very great.

In a small study, Dr. Thierry Vial, of Centre de Pharmacovigilance in Lyon and colleagues examined the risk of major malformations of the fetus among pregnant women who were treated with low-dose methotrexate in early-stage pregnancy.

A total of 28 cases were included in the final analysis, published in the Journal of Rheumatology.

Twenty-six of the women ended methotrexate treatment before 8 weeks of gestation. Four patients had spontaneous abortions and five had elective abortions.

Overall, there were a total of 19 live births. Of these, three were premature. The full-term children all had birth weights within the expected range, according to the investigators.

One child had minor anomalies, including a deformity of the feet and an eyelid angioma. One premature infant had jaundice, and another infant had transient respiratory distress and jaundice.

Methotrexate is an anti-folate drug, and this may be how it causes adverse effects, Vial’s team points out. They say it is therefore especially important for women on methotrexate to heed the recommendation for all women to take folate supplements before pregnancy.

“This recommendation also applies to patients without preconception folinic acid supplementation who have inadvertently continued methotrexate after the beginning of pregnancy,” they write

SOURCE: Journal of Rheumatology, December 2004.