Inal 2012.

Study characteristics
Methods	RCT, 2 arms, 100 randomised Setting: academic setting, Turkey Study period: January 2008‐March 2009 (unclear if recruitment period or entire study period)
Participants	Criteria related to previous IVF failure: yes, failed to conceive during 1 or more cycles of IVF and embryo transfer (ET) Inclusion criteria: women considered to be good responders to hormonal stimulation; age between 25 and 36 years Exclusion criteria: hydrosalpinx; thrombophilia; submucous myoma and factors found to have a negative impact on implantation
Interventions	Study group: 2 consecutive endometrial biopsies at 1‐week intervals during the luteal phase of the non‐transfer cycle, when on Gonadotropin‐releasing hormone agonist for downregulation. Endometrial biopsy was performed with a biopsy catheter (Pipelle de Cornier, Prodimed, Neuilly‐en‐Thelle, France) introduced through the cervical os and rotated within the uterine cavity 3‐4 times after withdrawal of the piston. Antibiotics were administered after the procedure Control group: no intervention
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage Obtained from author correspondence: ‐
Notes	Trial registration: believed to be: NCT01340560 (registered Apr 2011, registered retrospectively) Additional concerns and comments: Implantation and clinical pregnancy rates appear inconsistent; similar implantation rates reported in each arm (31% versus 35%) however clinical pregnancy rates significantly different (34% versus 60%); no obvious explanation. Funding: quote:"This study has no financial support" Author correspondence: yes, undertaken Publication: full‐text.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Paper states quote:"The randomization was based on a computer generated random numbers"
Allocation concealment (selection bias)	Unclear risk	No description provided
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	Low risk	Appears to be no attrition
Selective reporting (reporting bias)	High risk	Unclear if registered, and important outcomes such as adverse events not reported
Other bias	High risk	Trial registered retrospectively. There is an apparent inconsistency in the implantation and pregnancy rates reported, which are similar per arm for implantation rate but significantly different for clinical pregnancy rates.