Standardized IVF/ICSI-ET Procedure

IVF/ICSI-ET was performed according to the routine procedure of our center (11 (link)). Gonadotropins (Gn) including recombinant FSH (Merck Serono, Switzerland), urogenic FSH (Institut biochimique SA, Switzerland) and urogenic human Menopausal Gonadotropin (hMG) (Lizhu Pharmaceutical Co., Zhuhai) were initiated on the second day of menstruation bleeding. After 4-5 days injection of Gn, the serum levels of LH, E₂, and progesterone were tested, and the growth of follicles were checked by vaginal B-ultrasound. Human chorionic gonadotropin (r-hCG, Adze, 250ug) was applied that night, when three follicles ≥ 18mm (follicles ≥ 17mm for the antagonist regimen) were detected. With the guidance of transvaginal ultrasound, oocytes retrieval was performed 36-38h later. Luteal support and 9% vaginal progesterone gel (Swiss Merck Serono) were given to all patients. For the fresh cycle transfer, one or two embryos would be transferred 3/5 days after the oocyte retrieval if the patient was available, and the remaining embryos were cryopreserved. For the frozen cycle transfer, the endometrial preparation was carried out according to the diagnosis and treatment routine of our center (11 (link)). After the endometrial thickness of 8 mm monitored by ultrasound, progesterone 40 mg/day and vaginal progesterone gel 90 mg/day were performed which was set as D0. The embryo was transferred on D3/D5.