Bhattacharya 2008.

Methods	Trial design: parallel Multicentre (4 teaching hospitals, 1 general hospital), UK
Participants	Couples with unexplained subfertility, (mild male factor infertility and minimal endometriosis) N randomised: 509 with unexplained subfertility only (total 580) Age: TI + NC 32 years (± 3.4); TI + OH 32 years (± 3.5); IUI + NC 32 (± 3.7) Duration of subfertility: minimum 2 years, median 30 months all groups Basic fertility work‐up normal, semen normal according to WHO (sperm motility < 20% included) Previous treatment: not stated
Interventions	Comparison: TI (expectant management) + NC versus TI + OH versus IUI + NC Stimulation method: 50 mg CC/day (starting dose), day 2 to day 6 Ovulation: confirmed by progesterone measure in TI + OH group, and urinary LH surge in IUI + NC group Timing of IUI and TI: IUI 20 hr to 30 hr after LH surge, timing intercourse advised on cycle day 12 to 18 Duration of treatment: 6 cycles max
Outcomes	Live birth and PR per couple Miscarriage rate Ectopic PR Multiple pregnancies Pregnancy confirmed by USS showing gestational sac and foetal heart beat
Notes	The author provided additional data on the couples with unexplained subfertility only The baseline characteristics of the participants reported are from the group total. ITT analysis was therefore possible and performed Author provided additional information
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Sequence generated by independent statistician
Allocation concealment (selection bias)	Low risk	Adequate; central telephone randomisation system
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Blinding was not possible because of the nature of the interventions
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding was not possible because of the nature of the interventions and non‐blinding was not likely to affect the outcomes of interest
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow‐up and participants who received alternative treatment are presented in a flow‐chart; Nr of withdrawals: 4
Selective reporting (reporting bias)	Low risk	Live birth data and adverse events are published
Other bias	Low risk	Nothing detected