Tasdemir 2004.

Methods	Randomised, prospective, multi‐centre trial Method of randomisation: unknown Duration, timing and location of the trial: between September 2000 and December 2001 at 1 IVF centre in Turkey    Sample size calculation was not performed. 32 women were randomised. No drop‐out. One cycle per participant Ratio between metformin and placebo: 1:1 Intention‐to‐treat analysis was performed.
Participants	Clomiphene‐resistant women with PCOS . Women with type 1 or 2 diabetes were excluded. Mean age (±SD) was 31.8 (2.7) for the metformin group and 30.6 (3.2) for the placebo group. Body mass index (±SD) was 28.5 (3.5) and 29 (2.1), respectively. Duration of infertility (±SD) was 3.2 (0.9) and 3.8 (0.7) years, respectively. Infertility workup consisted of endocrinology, vaginal ultrasonography, hysterosalpingography or laparoscopy and semen analysis.
Interventions	Women took metformin 850 mg 2 times daily or placebo for 8 weeks. Metformin was continued daily during ovarian stimulation with rFSH until the day of hCG administration. Ovulation was induced with rFSH (follitropin alpha, gonal F). Treatment was started on day 3 after a spontaneous or induced menses. Starting dose was 75 IU rFSH (SC)/d for 7 days. If no ovarian response was noted, dose was increased until ovarian response was observed on ultrasonography. Treatment was discontinued if more than 6 follicles > 17 mm were present. hCG was given when 1 follicle of 17 mm developed.   Ovulation was assumed when progesterone level was > 5 ng/mL 6‐8 days after hCG.
Outcomes	Ongoing pregnancy rate per woman Ovulation rate Number of oocytes produced per cycle Monofollicular development and multi‐follicular development. Miscarriage rate per woman Quantity of gonadotrophins used per woman per cycle (total dose in IU (international units)) Duration (days) of ovarian stimulation per woman per cycle Serum oestradiol level on the day of hCG trigger injection Fasting insulin and glucose levels
Notes	PCOS: oligomenorrhoea and clinical or biochemical signs of hyperandrogenism Clomiphene‐resistant: failure to ovulate with incremental doses of clomiphene citrate up to 150 mg/d between 5th and 10th days of the cycle for 3 successive cycles Anovulation: progestogen levels < 5 ng/mL Oligomenorroe: fewer than 6 menstruations per year
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation was unknown.
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding was not performed.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Blinding was not performed.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No indication of loss to follow‐up or drop‐out was reported. All randomised women were included in the analysis.
Selective reporting (reporting bias)	Unclear risk	Not sure owing to missing details
Other bias	Unclear risk	Not sure owing to missing details