To assess the teratogenic risk of low dose weekly pulses of methotrexate (MTX) inadvertently taken during the first trimester of pregnancy.
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.
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.
In spite of the absence of congenital anomalies in our cases, safe contraception in fertile patients who start low dose weekly MTX is mandatory.