Ovarian stimulation in infertile women treated with the use of intrauterine insemination: a cohort study from China

Objective: To study the effectiveness of different ovarian stimulation protocols compared with natural cycle treatment in an intrauterine insemination (IUI) program. Design: Retrospective cohort study. Setting: Large reproductive medicine center. Patient(s): Couples with unexplained or mild male-factor infertility. Intervention(s): Couples were treated with the use of natural-cycle IUI, or IUI after ovarian stimulation with the use of clomiphene citrate (CC), letrozole, or gonadotropins. Main Outcome Measure(s): Live birth, multiple pregnancy rates, and cumulative live birth rates after three IUI cycles. Result(s): We performed 14,519 IUI cycles in 8,583 couples. Compared with natural-cycle IUI (6.2%), live birth rates were significantly higher in IUI cycles stimulated with the use of CC (8.9%), letrozole (9.4%) and gonadotropins (9.5%). The multiple pregnancy rate resulting from natural cycles was 0.7%, compared with 4.6% in CC cycles, 1.3% in letrozole cycles, and 4.2% in gonadotropin cycles. Cumulative live birth rates after three IUI cycles were 18.4% after natural-cycle IUI, and 25.7%, 26.2%, and 23.7% with the use of CC, letrozole, and gonadotropins, respectively. Conclusion(s): In an IUI program for unexplained or mild male-factor infertility, ovarian stimulation with letrozole may significantly increase live birth rates while controlling multiple pregnancy rates.