Tan 1999

Methods	Women 'randomly allocated' to 2 groups. Method of randomisation not reported
Participants	145 women (aged 18‐47 years) attending the family planning clinics in Guangzhou, China. Women had regular menstrual periods and attended the clinic within 72 h of a single act of unprotected intercourse
Interventions	Mife 12.5 mg orally, 2 doses, 12 h apart vs Mife 25 mg orally, 2 doses, 12 h apart
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 of women: Mife 12.5 mg twice 0/6/62; Mife 25 mg twice 2/5/83
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	Post‐randomisation exclusion and loss to follow‐up not reported
Selective reporting (reporting bias)	Low risk	Reported planned outcomes
Other bias	Low risk	None detected