Hur 2012.

Study characteristics
Methods	RCT, 2 arms, 59 randomised Setting: South Korea, Maria Fertility Hospital, one centre Recruitment period: no description
Participants	Criteria related to previous IVF failure: yes, first IVF cycle only Inclusion criteria: all patients were under 35 years old, day 3 follicle‐stimulating hormone level were below 10 IU/L. Exclusion criteria: infertility cause of uterine factor, severe male factor, and severe endometriosis were excluded.
Interventions	Study group: endometrial biopsy was done with a biopsy catheter (pipelle de cornier, France), performed only one time on starting day of stimulation. Control group: no procedure
Outcomes	Reported in paper: clinical pregnancy Obtained by author correspondence: ‐
Notes	Trial registration: authors confirmed trial was not registered Additional concerns and comments: none Funding: no description Author correspondence: yes, correspondence undertaken with Dr Yeonhee Ka (miriuh@daum.net) and Dr Hur (cyhur68@gmail.com). Authors provided the poster that was presented at the conference. Publication: abstract only (and poster)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Authors confirmed quote:"patient allocation was made by computerized randomization"
Allocation concealment (selection bias)	Unclear risk	No description
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was implemented
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only reported objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Only abstract available therefore difficult to assess level of attrition
Selective reporting (reporting bias)	High risk	Trial was not registered and important outcomes such as live birth and adverse events not reported
Other bias	High risk	Trial published as abstract only with limited detail, and further information not obtained from author correspondence. Trial not registered.