Multifollicular recruitment in combination with gonadotropin-releasing hormone antagonist increased pregnancy rates in intrauterine insemination cycles

ObjectiveTo determine whether including a GnRH antagonist in controlled ovarian stimulation–intrauterine insemination cycles would increase pregnancy rates.DesignProspective randomized study.SettingPrivate reproductive medicine clinic in Spain.Patient(s)Three hundred sixty-seven women with primary or secondary infertility.Intervention(s)Patients were randomly assigned to controlled ovarian stimulation with recombinant FSH (75–150 IU/d) alone (controls, n = 183) or with recombinant FSH (75–150 IU/d) + the GnRH antagonist (0.25 mg/d), initiated when the recruited follicles were ≥16 mm (n = 184). A single insemination was performed, 36–38 hours after hCG (5,000 IU, IM), in both groups.Main Outcome Measure(s)Follicular recruitment, pregnancy rates.Result(s)Numbers of mature follicles (2.4 ± 1.3 vs. 1.3 ± 1.09) and clinical pregnancy rates (23% vs. 11%) were statistically significantly higher in patients who were treated with GnRH antagonist than in those who were in the control group. The pregnancy rate was only higher in the antagonist group if more than one follicle sized ≥18 mm was present on the day that the hCG was given. A similar number of twin pregnancies occurred in both groups: two in the antagonist group and three in the control group. The antagonist group also had one triplet gestation.Conclusion(s)Adding GnRH antagonist to controlled ovarian stimulation–intrauterine insemination cycles significantly increases pregnancy rates in multifollicular, but not monofollicular, cycles.