Comparison of a novel flexible progestin primed ovarian stimulation protocol and the flexible gonadotropin-releasing hormone antagonist protocol for assisted reproductive technology.

<bold>Objective: </bold>To determine whether a flexible progestin primed ovarian stimulation (fPPOS) protocol is effective for preventing premature ovulation.<bold>Design: </bold>Retrospective cohort study.<bold>Setting: </bold>Private assisted reproduction center.<bold>Patient(s): </bold>Eighty-seven oocyte donors and 191 recipients of fresh oocytes.<bold>Intervention(s): </bold>Each donor was stimulated with a flexible gonadotropin-releasing hormone (GnRH) antagonist protocol in one cycle and with the new fPPOS protocol in the other, within a period of 6 months. FSH was started on cycle day 2-3, and 0.25 mg/day GnRH antagonist or 10 mg/day medroxyprogesterone acetate (MPA) was started on stimulation day 7 or when the leading follicle reached 14 mm, whichever came first.<bold>Main Outcome Measure(s): </bold>Duration of stimulation, gonadotropin consumption, duration of GnRH antagonist or MPA administration, number of metaphase II oocytes, and pregnancy rates in fresh oocyte recipients.<bold>Results: </bold>Duration of stimulation was 11 (10-11) days in both groups. Total gonadotropin consumption was similar. Pituitary suppression was started on day 7 and lasted for 5 days in each group. There were no premature ovulations in any group. The fPPOS yielded a significantly higher number of cumulus oocyte complexes than GnRH antagonist cycles (33 [21-39] vs. 26 [18-36], respectively). Likewise, the fPPOS generated significantly more metaphase II oocytes than GnRH antagonist cycles (24 [17-34] vs. 21 [15-28], respectively). Recipients of fresh oocytes from fPPOS and GnRH antagonist cycles had similar cleavage, blastulation, implantation, and live birth/ongoing pregnancy rates (50% vs. 48.6%).<bold>Conclusion(s): </bold>FPPOS with MPA seems to be an effective choice for preventing premature ovulation in women undergoing ovarian stimulation without compromising oocyte quality. [ABSTRACT FROM AUTHOR]