Patients and study design
A retrospective study of infertile women with normal ovarian reserve attending the Assisted Reproduction clinic, Shanghai First Maternity and Infant Hospital for IVF from January 2017 to December 2019 was undertaken, and each patient was followed for 18 months from the day of the ovarian stimulation. Ethical approval was not required for the retrospective analysis.
Women were included if they fulfilled the following inclusion criteria: (i) less than 40 years of age; (ii) having indications for IVF; (iii) regular menstrual cycles over the previous 3-month period (25 - 35 days in duration); (iv) antral follicle count (AFC) of more than 5 on menstrual cycle day 2 - 3, and basal serum FSH concentration of no more than 10 IU/L. Women were excluded if they had: (i) diagnosis of polycystic ovarian syndrome, (ii) an abnormal uterine cavity shown on hysterosalpingogram or hysteroscopy, (iii) moderate or severe endometriosis, (iv) use of donor eggs/sperm, (v) preimplantation genetic testing, (vi) rescue intracytoplasmic sperm injection (ICSI) or half ICSI, (vii) still having cryopreserved embryos but continuing to the next fresh IVF cycle.
Women were offered either progestin-primed ovarian stimulation protocol (PPOS group) or agonist long protocol (agonist group) at the discretion of the attending physicians or subject to the wishes of the couple.