Study	Reason for exclusion
Demirol 2006	Not a randomised controlled trial
Egbase 2001	Data were not properly reported. The study did not state how many participants withdrew from each group (1 and 2). Moreover, the author does not present the means and standard deviations (SD) nor the standard errors (SE)
Geusa 2002	The study was excluded because of data irregularities (summarised reported data were not consistent with table data). We were not successful in contacting the authors to clarify the queries
Kahraman 2001	Control group was treated with oral contraceptives instead of placebo or no treatment
Palomba 2011b	Participants were poor responder women
Schachter 2007	Participants specifically undergoing ICSI were not randomised separately
Stadtmauer 1999	It is not a randomised controlled trial Prospective controlled analysis Participants acted as their own control, when metformin was used in the subsequent cycle
Stadtmauer 2001	It is not a randomised controlled trial Retrospective data analysis
Stadtmauer 2002	The study is not a randomised controlled trial
Tasdemir 2004	Participants undergoing ovulation induction cycles; not IVF or ICSI cycles

ICSI: intracytoplasmic sperm injection
 IVF: in vitro fertilisation