L-arginine for uterine blood flow

L-arginine is a nitric oxide precursor that dilates blood vessels, including uterine arteries. A 2025 RCT found oral L-arginine 3g/day for 20 days reduced uterine artery resistance and raised clinical pregnancy rate from 11.1% to 38.9% in women with recurrent implantation failure.

An earlier trial in poor-responder IVF patients showed lower cancellation rates, more oocytes and embryos, and better Doppler blood flow measurements.

This is a targeted intervention for specific populations (RIF, poor ovarian response), not a general fertility supplement. Discuss with your provider if you have a history of implantation failure.