Objective: To assess the teratogenic risk of low dose weekly pulses of methotrexate (MTX) inadvertently taken during the first trimester of pregnancy.
Methods: We assessed pregnancy and neonatal outcome of 4 patients with rheumatic disease treated with weekly pulses of 5 to 15 mg of MTX for a mean duration of 4 years.
Results: The 4 patients had continued MTX treatment from one to 6 weeks of gestation. One patient miscarried at Week 6, the other pregnancies ended with the delivery of healthy children. Chromosome analysis of one child was normal.
Conclusion: In spite of the absence of congenital anomalies in our cases, safe contraception in fertile patients who start low dose weekly MTX is mandatory.