Comparison of low-dose human menopausal gonadotropin and micronized 17β-estradiol supplementation in in vitro maturation cycles with thin endometrial lining

Objective: A challenge of in vitro maturation (IVM) treatment in some women is insufficient development of the endometrium prior to embryo transfer. Design: Retrospective study. Setting: McGill Reproductive Center, Montreal, Canada. Patient(s): Women with endometrial thickness <6 mm on days 6-10 ultrasound (US) scan of IVM treatment. Intervention(s): In the human menopausal gonadotropin (hMG) group, 150 IU/day of hMG was started and in the estradiol group, 6 to 12 mg/day of micronized 17β-estradiol was initiated. Additional US scans were performed 2 to 3 days apart, until endometrial thickness reached ≥8 mm or a dominant follicle (>10 mm) was identified. Main Outcome Measure(s): Endometrial lining before oocyte retrival. Result(s): In both groups endometrial lining significantly thickened following treatment. However, hMG treatment resulted in a higher number of follicles ≥7 mm compared to estradiol (7.4 ± 4.8 vs. 3.4 ± 2.5, respectively) and a significantly higher percentage of mature oocytes that were identified on the day of oocyte retrieval (in vivo matured oocytes) (15.1% vs. 10.5%). Conclusion(s): In IVM designated cycles with a thin endometrium both low-dose hMG and micronized 17β-estradiol supplementation significantly improve endometrial thickness. However, low-dose hMG results in larger follicles and a greater number of in vivo matured oocytes.