IVF-ET procedures and PGT-A
ovarian hyperstimulation
OVARIAN HYPERSTIMULATION
OS, oocyte retrieval, fertilization, blastocyst culture, endometrial preparation, embryo transfer, and luteal phase support were performed according to standard protocols in our IVF center, as previously described in detail [Briefly, a flexible antagonist protocol for controlled ovarian hyperstimulation was used for each participant, with recombinant human FSH (Gonal-f; Merck Serono, Geneva, Switzerland) or human menopausal gonadotropin (HMG, Livzon, Zhuhai, China) initiated on the 2nd or 3rd day of the menstrual cycle at a starting dose of 150–300 IU/day, adjusted for age, BMI, antral follicle count (AFC), FSH, and anti-Mullerian hormone (AMH) levels. Gonadotropin-releasing hormone antagonist (Cetrotide; Merck Serono) was administered at a dose of 0.25 mg/day when the dominant follicle reached 14 mm in size or the serum E2 level reached 350 pg/ml. This treatment continued until the leading follicle reached 18 mm or two follicles reached 16 mm in size. Subsequently, a dose of 5,000–10,000 IU of human chorionic gonadotropin (Livzon, Zhuhai, China) was administered as a trigger, and oocytes were retrieved 36 h later.Intracytoplasmic sperm injection and blastocyst culture were performed for all participants following IVF laboratory guidelines, and next-generation sequencing-based PGT-A was administered to all blastocysts obtained using a NextSeq CN500 sequencer (Illumina, Inc. San Diego, CA, USA) according to the manufacturer’s instructions [