Endocrine Abstracts

Background: Aromatase inhibitors have been introduced as a new treatment modality in controlled ovarian stimulation as they were found to elevate follicular sensitivity to gonadotropins.

The purpose of this study was to evaluate whether IVF outcomes will differ between poor responder patients who receive high doses of gonadotropins alone or low doses of gonadotropins with letrozole during ovulation stimulation.

Methods: Patients who underwent in vitro fertilization treatment classified as poor responder patients according. Inclusion criteria: patients being aged between 18 and 42 years, having regular menstrual cycles (between 25–32 days), having normal BMI (between 19.3–28.9 kg/m.), having normal hormone levels, having normal endometrium (evaluated with hysteroscopy). Exclusion criteria: chemotherapy and radiotherapy, ovarian surgery in anamnesis. The controlled ovarian stimulation were started on third day of the menstrual cycle. In the I Group, 24 patients were treated with 150 IU gonadotropins in combination with letrozole 5 mg/day for the first five days of the stimulation. In the II Group, 32 patients were treated with 300 IU gonadotropins. Patients were treated with 0.25 mg GnRH antagonist given from stimulation day 6 onwards. When at least three follicles were 18 mm in size, a single dose of 250 µg hCG was injected for follicular maturation. Oocyte retrieval took place for the 34–36 hours after hCG trigger. Oocytes were fertilized by conventional ICSI and cultured until the day of embryo transfer.

Results: Group I and II, there were no statistically significant difference in duration of ovulation stimulation, duration of antagonist use, number of retrieved oocytes, number of transferred embryos, implantation rate, clinical and ongoing pregnancy rates (P > 0.05). Gonadotropin use was significantly higher in Group II (300 IU gonadotropins) compared to I Group (150 IU gonadotropins in combination with letrozole 5 mg/day), (P < 0.05).

Conclusion: Using letrozole with low doses of gonadotropins in patients with POR does not improve the pregnancy outcomes compared to high doses of gonadotropins alone. However, the addition of letrozole can make pregnancy outcomes comparable using significantly lower doses of gonadotropins, so may be regarded as an effective adjuvant agent in POR patients.