Zhang 1998

Methods	Randomised trial. Method of randomisation not reported
Participants	309 women attending family planning clinics in Beijing, China Included only women attending within 72 h of an unprotected intercourse Excluded women with irregular menstrual periods, who used oral contraceptives and those who had not resumed normal menses after an abortion or delivery
Interventions	Mife 25 mg vs Mife 10 mg vs Mife 5 mg
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Post‐randomisation exclusions not reported Loss to follow‐up 5.8% (18/309) altogether Observed pregnancy/expected pregnancy/total number of women: Mife 25 mg 1/6/99; Mife 10 mg 1/7/92; Mife 5 mg 2/7/100
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	Low risk	Loss to follow‐up reported
Selective reporting (reporting bias)	Low risk	Reported planned outcomes
Other bias	Low risk	None detected