Guven 2014.

Study characteristics
Methods	RCT, 2 arms, 124 randomised Setting: Turkey, academic clinic, one centre Recruitment period: September 2010 ‐ April 2011
Participants	Criteria related to previous IVF failure: yes, women were undergoing their first IVF cycle (as per author correspondence) Inclusion criteria: age < 35; history of primary infertility; normal responder (antral follicle count of 5 to 10 in 1 ovary at early follicular phase); grade I or II embryos for transfer Exclusion criteria: endocrinopathies; any systemic disease; history of neoplasm; high risk for or history of ovarian hyperstimulation syndrome; use of any concurrent medication; failure to proceed to follicle retrieval; severe male infertility requiring testicular sperm aspiration; Mullerian tract anomalies; history of endometrial instrumentation or surgery within 1 month of the study; fibroids and other uterine factors (polyps, adhesions); lack of agreement to undergo endometrial biopsy during the stimulation cycle
Interventions	Study group: endometrial injury was performed on day 3 of the menstrual cycle following down regulation; the scratching was done in 2 defined (anterior and posterior) portions of the uterine cavity under sterile conditions with the use of a biopsy catheter (Gynetics 4164 Probet Pipella, HD Aksu Medical, Ankara, Turkey) Control group: n o intervention
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage Obtained by author correspondence: ‐
Notes	Trial registration: NCT01851876 (registered May 2013, registered retrospectively) Additional concerns and comments: trial recruited 124 women in 8 months from 1 centre (16 per month), which is a high recruitment rate for such a short recruiting window. Funding: unclear Author correspondence: yes, undertaken with the first author drsuleymanguven@yahoo.com Publication: full‐text.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Trial registration describes study as non‐randomised. Described in paper as quote: "prospective case–control study" and also as an RCT "Women were allocated at random (sealed envelopes) to the intervention group or the control group" author correspondence confirmed the trial was an RCT with computer‐assisted randomisation
Allocation concealment (selection bias)	Unclear risk	Sealed envelopes were used, unclear if SNOSE
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was employed
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only objective outcomes reported
Incomplete outcome data (attrition bias) All outcomes	High risk	The eligibility criteria include having grade I or II embryos to transfer and no 'failure to proceed to follicle retrieval' which are post‐randomisation exclusions as the women in the intervention arm underwent endometrial injury prior to follicle retrieval. It is unclear how many women were excluded for these reasons.
Selective reporting (reporting bias)	High risk	Trial registered retrospectively and adverse outcomes such as pain not reported
Other bias	High risk	Trial registered retrospectively.