Intrauterine insemination (IUI) with or without letrozole for unexplained or mild male factor infertility: a randomized pilot study

Abstract Objective To study the feasibility of a randomized controlled trial (RCT) comparing intrauterine insemination (IUI) with and without letrozole in couples with unexplained or mild male factor infertility Study design We performed a randomized pilot study including 100 couples with unexplained or mild male factor infertility in the Reproductive Medicine Centre of Peking University Third Hospital in China. The couples scheduled for IUI were randomized to IUI with or without ovarian stimulation (letrozole) for up to 3 cycles within a time horizon of 4 months. Women in the letrozole group received 5 mg oral letrozole daily starting from cycle day 3-5 for 5 days. Women in the natural cycle IUI group did not receive any ovarian stimulation before IUI. The primary outcome is ongoing pregnancy leading to live birth. The study was registered under trial number NCT03455426 Results Between March 2018 and January 2019, 158 couples were eligible to participate after initial screening and 100 (63.3%) couples agreed to participate. Of the 100 recruited couples, 50 were randomly allocated to IUI with letrozole and 50 to natural cycle IUI. Live birth occurred in 12 women (24.0%) in the letrozole group and 10 women (20.0%) in the natural cycle group (RR 1.20 (95% CI 0.57 to 2.52)). Clinical pregnancy rates were 28% and 26% in the letrozole group and natural cycle group respectively (RR 1.08 (95% CI 0.56 to2.05). There were no multiple pregnancies in both groups. Patients were willing to be randomized and useful information was gained to plan a definitive trial. Conclusions We showed that an RCT comparing IUI with letrozole versus natural cycle IUI in couples with unexplained or mild male factor infertility is feasible and acceptable.