Effects of human menopausal gonadotropin on zona pellucida and pregnancy outcomes of ovarian stimulation protocols

Background: Human menopausal gonadotropin (hMG) has contributed many improvements to human assisted reproduction. However, effects of hMG on oocyte development and clinical results remain controversial. Objective: This study was conducted to investigate the effects of hMG on the zona pellucida of oocytes, as well as clinical results in superovulation treatment. Materials and Methods: This retrospective study was performed with 150 cycles of long-protocol treatment using recombinant follicle-stimulating hormone (r-FSH) with or without hMG. The number of retrieved oocytes, fertilization rate, implantation rate, pregnancy rate, and birefringence and thickness of the zona pellucida of oocytes were investigated. Results: No significant differences were existed in r-FSH +hMG, and r-FSH groups in the number of retrieved oocytes (11.99±0.75 vs. 13.9±0.73, p=0.06), maturation rate (84.76% vs. 83.32%, p=0.42), pregnancy rate (37.31% vs. 37.66%, p=0.96), and embryo implantation rate (28.97% vs. 23.26%, p=0.30). However, fertilization rate (82.95% vs. 78.75%; p=0.02) was different. Zona pellucida birefringence was lower in the r-FSH +hMG group than in the r-FSH group (6.70±0.50 vs. 7.04±0.31; p=0.53). Thickness values of the metaphase-II zona pellucida of the r-FSH +hMG group on the first (19.20±0.14 vs. 18.75±0.10; p=0.01) and second (18.69±0.12 vs. 18.17±0.14; p=0.00) days of insemination were both higher than those of the r-FSH group. Conclusion: hMG positively influenced the improvement of oocyte fertilization, as well as the birefringence and thickness of zona pellucida.