Letrozole and gonadotropins versus luteal estradiol and gonadotropin-releasing hormone antagonist protocol in women with a prior low response to ovarian stimulation

Objective: To compare in vitro fertilization outcomes after ovarian stimulation using letrozole/antagonist (LA) versus luteal-phase estradiol (E-2)/gonadotropin-releasing hormone (GnRH) antagonist (LPG) in poor responders. Design: Retrospective study. Setting: Academic center. Patient(s): Ninety nine women with >= 2 prior cycles, at a starting dose of >= 300 IU gonadotropins, who yielded fewer than five oocytes or a prior cycle cancellation. Intervention(s): In the LPG group (n = 52), transdermal E-2 initiated every other day starting day 10 after the luteinizing hormone (LH) surge; one day 11, patients began daily administration of antagonist for 3 consecutive days, with gonadotropins started on the second day of menstruation. In the LA group (n = 47), letrozole 5 mg/day initiated on the second day of spontaneous menstruation for 5 days then gonadotropins added on day 5; for both groups a flexible antagonist protocol was used. Main Outcome Measure(s): Ongoing pregnancy, number of oocytes retrieved, and cancellation rate. Result(s): The total dose of gonadotropins administered and E-2 levels on day of hCG administration were statistically significantly lower with the LA protocol. The number of oocytes retrieved (6.1 +/- 3.0 vs. 7.9 +/- 4.8), number of transferred embryos (2.2 +/- 1.0 vs. 2.4 +/- 1.4), and cancellation rate (55.3% vs. 36.5%) were similar in both groups. Ongoing pregnancy rates per transfer (40% vs. 21.2%) and per initiated cycle (19.1% vs. 13.5%) were similar in the LA and LPG groups, respectively. Conclusion(s): Aromatase inhibitor regimens can be a feasible alternative to the LPG protocol in recurrent low ovarian response. (Fertil Steril (R) 2011; 95: 2330-4. (C) 2011 by American Society for Reproductive Medicine.)