Ovarian stimulation in in vitro fertilization with or without the "long" gonadotropin-releasing hormone agonist protocol: effect on cycle duration and outcome

OBJECTIVE: To study the correlation between stimulation duration of IVF cycles, with and without GnRH agonist (GnRH-a), and cycle outcome. DESIGN: Retrospective analysis of data. SETTING: University-affiliated IVF clinic. PATIENT(S): 998 IVF cycles in which long GnRH-a protocol was used, and 155 cycles with hMG only. INTERVENTION(S): IVF cycles. MAIN OUTCOME MEASURE(S): Cycle outcome in number of oocytes and embryos, and pregnancy rate. RESULT(S): The mean stimulation duration (+/-SD) was 9.6+/-1.7 and 6.7+/-1.0 for the GnRH-a and the hMG-only cycles, respectively (P<0.01). In the GnRH-a group, no statistically significant correlation between cycle duration and pregnancy rate was found. Interestingly, the patients treated for 9 days had the highest number of oocytes retrieved and the highest pregnancy rate. Stimulation duration was not affected by age in either protocol. GnRH-a cycles yielded a significantly higher number of oocytes and embryos compared to cycles without GnRH-a. The pregnancy rate was similar in both groups. CONCLUSION(S): Stimulation duration in the long GnRH-a protocol group was significantly longer than in the hMG-only group. Stimulation duration was not affected by age. No statistically significant correlation was found between stimulation duration and cycle outcome in the long protocol group.