PACTR201505001142202.

Methods	A prospective study (in the trial registration it is stated to be a RCT) El Shatby Hospital, Alexandria Egypt. Dates of enrolment not reported
Participants	200 participants with BMI ≥ 35 kg/m2 and normal blood glucose, HbA1C and plasma insulin, in the early second trimester
Interventions	Experimental intervention: metformin 500 mg twice a day versus placebo. 100 women enrolled Control intervention: placebo. 100 women enrolled
Outcomes	Pre‐eclampsia GDM Birthweight
Notes	Minimal clinical outcomes No funding sources reported. Authors report no conflicts of interest. More information requested about all criteria for 'Risk of bias' assessment ‐ 15/03/2018
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were divided into two groups.
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Participants received "placebo", although it was not stated if the placebo had an identical appearance.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcomes were reported on all women enrolled in the study.
Selective reporting (reporting bias)	High risk	1 of 2 specified outcomes was not reported.
Other bias	Low risk	None identified