Lensen 2019.

Study characteristics
Methods	RCT, 2 arms, 1364 randomised Setting: 13 academic/public hospital centres across five countries (New Zealand, Australia, UK, Belgium, Sweden) Recruitment period: June 2014 ‐ June 2017
Participants	Criteria related to previous IVF failure: no Inclusion criteria: women planning IVF with their own oocytes (stimulated IVF cycle with planned fresh transfer, or frozen embryo transfer using stored embryos) Exclusion criteria: not planning an embryo transfer (e.g. fertility preservation or planned freeze‐all cycles), had any contraindication to pipelle biopsy (e.g. vaginismus), or had undergone any disruptive intrauterine procedures within three months prior to commencing IVF, specifically: hysteroscopy, sonohysterogram, hysterosalpingogram, laparoscopy, surgically managed miscarriage or endometrial biopsy
Interventions	Intervention: single endometrial pipelle biopsy performed between day 3 of the menstrual cycle preceding the embryo transfer cycle and day 3 of the menstrual cycle for which embryo transfer is planned Control: no procedure
Outcomes	Reported in paper: live birth, clinical pregnancy, miscarriage, multiple pregnancy, pain, bleeding Obtained by author correspondence: ‐
Notes	Trial registration: ACTRN12614000626662 (registered June 2014, registered prospectively) Additional concerns and comments: none Funding: University of Auckland, New Zealand; the A+ Trust, Auckland District Health Board, New Zealand; the Nurture Foundation, New Zealand; and the Maurice & Phyllis Paykel Trust, New Zealand Author correspondence: yes, one of the investigators is an author on this Cochrane Review (s.lensen@auckland.ac.nz) Publication: full‐text.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "An online, third‐party, data collection and randomisation system was used... participant allocations were concealed within the system until the patient was randomised. Participants were randomised in a 1:1 ratio using block randomisation of two different sizes between 6 and 16 repeating in random order, stratified by recruiting site and by whether a fresh or frozen embryo transfer was planned"
Allocation concealment (selection bias)	Low risk	As above
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding was used. A higher proportion of women in the endometrial injury arm underwent embryo transfer compared to women in the control arm; however there was no impact on the results after adjusting for this observation
Blinding of outcome assessment (detection bias) All outcomes	High risk	The outcome of pain during the procedure and bleeding were self‐reported by participants who were not blind to their treatment allocation
Incomplete outcome data (attrition bias) All outcomes	Low risk	Minimal attrition: four women withdrew from the trial and the pregnancy outcome of one further women is unknown
Selective reporting (reporting bias)	Low risk	Trial was registered prospectively and the protocol published; all outcomes reported
Other bias	Low risk	‐