Qi 2000a

Methods	Double‐blind, randomised, multicentre trial Random number generation done centrally. Double‐blinded by use of identical placebos
Participants	1209 women attending the family planning clinics in 11 provinces of China. Women had regular menstrual periods and attended the clinic within 72 h of a single act of unprotected intercourse
Interventions	Mife 25 mg vs Mife 10 mg, single dose
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Total of 85 cases lost to follow‐up or missed data (7.03%) Observed pregnancy/expected pregnancy/total number women: Mife 25 mg 5/91/579; Mife 10 mg 12/78/545
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number generation done centrally
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not mentioned
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐blind
Incomplete outcome data (attrition bias) All outcomes	Low risk	Lost to follow‐up reported
Selective reporting (reporting bias)	Low risk	Reported planned outcomes
Other bias	Low risk	None detected