Zhang 2000

Methods	Women 'randomly allocated' into 4 groups
Participants	782 women attending a hospital clinic in Qinhai, China. Women had regular menstrual periods and attended the clinic within 72 h of a single act of unprotected intercourse
Interventions	Mife 25 mg, 2 doses, 12 h apart vs LNG 0.75 mg, 2 doses, 12 h apart vs Mife 25 mg, single dose vs Mife 25 mg + LNG 0.75 mg
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Post‐randomisation exclusion and loss to follow‐up not reported Observed pregnancy/expected pregnancy/total number women: Mife 25 mg twice 1/15/212; LNG 1/16/205; Mife 25 mg 3/13/182; Mife 25 + LNG 4/13/183
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Mentioned randomisation but description not adequate
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not mentioned
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No mention of post‐randomisation exclusion and loss to follow‐up
Selective reporting (reporting bias)	Low risk	Reported planned outcomes
Other bias	Low risk	None detected