Fig. 1

Schematic representation of the study protocol for the DNG group and control group

In the control group, patients received standard controlled ovarian hyperstimulation with mid-luteal phase GnRH agonist down-regulation. Nasal spray GnRH agonist was administered from the mid-luteal phase in the previous cycle to the time of HCG injection for the ovulation induction of the IVF-ET cycle. Controlled ovarian hyperstimulation was initiated from the second day of the IVF-ET cycle by FSH and HMG. In the DNG group, DNG was administered orally every day for 12 weeks from 3 months prior to the IVF-ET cycle. Withdrawal bleeding was induced using E and P. Controlled ovarian hyperstimulation was given in a manner similar to that in the control group. GnRH agonist: buserelin acetate 900 mg/day; E: conjugated estrogen; P: dydrogesterone; M: menstruation; FSH: follicle-stimulating hormone; HMG: human menopausal gonadotropin; HCG: human chorionic gonadotropin; OPU: ovum pick-up; DNG: dienogest; dinagest, 2 mg/day.