Outcome measures
dysplasia, OHSS
OVARIAN HYPERSTIMULATION SYNDROME, DYSPLASIA, CAVITY, ECTOPIC PREGNANCY
The primary outcome was the cumulative pregnancy rate for all participants. Secondary outcomes included the characteristics and clinical pregnancy rates of all intervention cycles. These characteristics were listed as follows: (i) ovulation characterized by a decrease in ovarian follicles and fluid in the pouch of Douglas, detected through B-mode ultrasonography 2 days after HCG administration; (ii) cancellation cycle referred to a cycle that has been discontinued due to premature ovulation, follicular dysplasia, or ovarian hyperstimulation syndrome (OHSS); (iii) biochemical pregnancy defined as a positive β-HCG pregnancy test 2 weeks after ovulation, clinical pregnancy defined as the observation of a gestational sac with fetal echoes and primitive cardiac tube pulsation inside the uterine cavity via B-ultrasound 2 weeks after a positive pregnancy test, singleton pregnancy (the sample for singleton pregnancies was derived from ongoing pregnancies), multiple pregnancy, early abortion(gestational age ≤ 14 weeks), ectopic pregnancy; (iv) duration of FSH treatment; (v) rate of one mature follicle (diameter ≥ 18 mm) and ovulation with one follicle; (vi) days required for follicles to mature and ovulate; (vii) sex hormone concentration on HCG injection day; (viii) endometrial thickness on HCG injection day and ovulation day.