Hwang 2004.

Methods	Single‐centre, parallel group study. Number of women recruited: 60. Number of women excluded: 4 (2 refused to participate, 2 did not meet inclusion criteria). Number of women randomized: 56 (27 in intervention group; 29 in control group). Number of withdrawals: 7 (2 in intervention group: 1 due to poor ovarian response, 1 due to personal reasons; 5 in control group: 2 due to inadequate ovarian response, 3 due to risk of severe OHSS). Number of women analyzed: 49.
Participants	Country: Taiwan. Inclusion criteria: PCOS. Exclusion criteria: diagnosis of congenital adrenal hyperplasia, Cushing's syndrome, androgen‐producing tumours, hyperprolactinaemia or thyroid dysfunction; aged > 38 years; serum FSH levels > 12 mIU/mL. Mean age ± SD: intervention group: 31.4 ± 3.5 years; control group: 31.7 ± 3.7 years
Interventions	Intervention: COCP (Diane‐35, oral) on cycle days 5‐25 for 3 consecutive cycles + GnRH antagonist (cetrorelix acetate 0.25 mg single dose, SC on post‐treatment day 3; 0.125 mg/day on post‐treatment days 4‐9; and 0.25 mg/day started post‐treatment day 10 + hMG 150 IU/day), started post‐treatment day 4. Control: GnRH agonist (buserelin acetate 500 μg/day, long protocol) started day 3 of induced or spontaneous menstruation, and 250 μg/day started day of ensuing pituitary downregulation + hMG (150 IU/day) for 6 days started when pituitary downregulation was achieved. hMG dose can be adjusted according to woman's follicular response. Pituitary downregulation achieved when serum oestradiol levels < 50 pg/mL and there was an absence of ovarian cysts > 10 mm in diameter. Both GnRH analogues and hMG were continued until hCG injection (10,000 IU, IM), administered when ≥ 2 follicles reached 18 mm in diameter with adequate oestradiol response.
Outcomes	Fertilisation. Clinical pregnancy: presence of ≥ 1 foetal heart beat confirmed with ultrasound, performed 7 weeks after embryo transfer. Implantation rates. Serum LH and testosterone status upon starting and during hMG administration. Total days and amount of gonadotrophins administered: measured in ampoules. Pregnancy loss. Multiple pregnancy rate: ongoing or live born. OHSS: not defined.
Notes	Power calculation performed: yes. ITT analysis performed: no
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was done by opening sealed envelopes containing computer‐generated block randomization numbers with a block size of 10."
Allocation concealment (selection bias)	Low risk	Sealed envelopes.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Quote: "The laboratory staff were blinded to the stimulation protocol." Unclear if treating physicians were blinded.
Incomplete outcome data (attrition bias) All outcomes	High risk	Reasons for withdrawals and proportions of withdrawals were not balanced between groups and data were not analyzed on the basis of ITT.
Selective reporting (reporting bias)	Low risk	Data on all planned outcomes were reported.
Other bias	Low risk	No significant difference in baseline characteristics with regard to age, duration of infertility, BMI and hormonal levels.