Thyagaraju 2020.

Study characteristics
Methods	Randomised controlled trial, 2 groups, set in Infertility outpatient clinic in OBG Department, Pondicherry, India June 2017 to June 2019 Number of participants randomised: 168 (confirmed by author correspondence) Number of participants analysed: 162
Participants	Inclusion criteria: age of female partner 20 to 35 years; couples with mild male factor infertility, defined according to WHO (2010); couples with unexplained infertility (regular normal menstrual cycles, bilateral fallopian tubes patent (confirmed by laparoscopy or hysterosalpingography), normal TSH and prolactin levels, normal reproductive hormone levels, normal semen analysis) Exclusion criteria: ovarian endometriosis or intrauterine organic pathology (polyps, myoma, and adhesions); known pelvic inflammatory disorder; ovarian cyst; any other medical disorder (cardiovascular, renal, and hepatic disorders); poor ovarian reserve Cause of infertility: unexplained, mild male factor infertility
Interventions	Intervention group: endometrial scratching performed on Day 8 or 9 of the stimulated IUI cycle Control group: no endometrial scratching Both groups: ovarian stimulation with clomiphene citrate and gonadotropins followed by IUI Degree of endometrial injury: pipelle Timing of endometrial injury: follicular phase (on Day 8 or 9) of the stimulated IUI cycle. Endometrial scratching was performed in all 3 cycles Study length: 3 cycles Type of conception: IUI
Outcomes	Reported in the abstract: Clinical pregnancy rate (author correspondence: "ultrasound confirmation of gestational sac with fetal cardiac activity") Abortion (author correspondence: defined as "number of pregnancy losses before 20 weeks of gestation or less than 500 grams of weight", and confirmed that all pregnancy losses were clinical pregnancy losses ‐ not biochemical pregnancy losses) Multiple pregnancy Pain after the procedure (visual analogue scale (VAS)) Bleeding after the procedure (author correspondence confirmed bleeding was graded as mild/moderate/severe based on wetness of a pad 15 minutes after the procedure) Obtained by author correspondence: Live birth Ongoing pregnancy (all women with an ongoing pregnancy had a live birth)
Notes	Only a conference abstract was available Funding source: not reported Conflicts of interest: not reported Trial registration: CTRI/2017/10/010056 (retrospectively registered) Author correspondence was undertaken
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Author correspondence confirmed that randomisation was performed by "computer generated random sampling" with "varying block size of 4‐6" Although the method of random sequence generation was adequate, we noticed a baseline imbalance in duration of infertility
Allocation concealment (selection bias)	Low risk	Author correspondence confirmed that sealed, opaque, sequentially numbered envelopes were used to conceal allocation
Blinding of participants (performance bias)	High risk	Author correspondence confirmed that participants were not blinded. Lack of participant blinding is anticipated to introduce performance bias
Blinding of personnel (performance bias)	High risk	Author correspondence confirmed that personnel were not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Author correspondence confirmed there was no blinding. Study recorded patient‐reported outcomes (pain and bleeding after the procedure). Lack of participant blinding could introduce detection bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	Author correspondence confirmed that in total 6 women were excluded from the analysis. Four women withdrew from the trial: 2 women in the intervention group (due to unruptured follicle and participant not willing to undergo endometrial scratching) and 2 women in the control group (due to unavailable husband and sub‐optimal semen sample). Two women were lost to follow‐up (1 in each group). Missing outcome data were balanced in numbers across intervention groups; therefore the study was rated at low risk of attrition bias
Selective reporting (reporting bias)	Unclear risk	Trial was registered retrospectively
Other bias	Low risk	We did not identify any other potential sources of bias