Sheng 2008

Methods	Women randomly allocated to 2 groups. Method of randomisation not reported
Participants	200 women attending in a family planning clinic, Tongxiang, Zhejiang, China. Women had regular menstrual periods and a single act of unprotected intercourse within 72 h of attending the clinic
Interventions	LNG‐COC, 4 tablets (total ethinyl oestradiol 0.12 mg and LNG 0.6 mg) 2‐dose, 12 h apart, orally vs LNG 0.75 mg, 2‐dose, 12 h apart, orally
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Observed pregnancy/total number of women: LNG‐COC: 1/100; LNG: 1/100 Side effects: LNG‐COC: nausea 33/100; vomiting 5/100; dizziness and fatigue 12/100  LNG: nausea 15/100; vomiting 3/100; dizziness and fatigue 9/100 Changes in menstrual pattern:  Early: LNG‐COC 10/100; LNG 14/100 Delay: LNG‐COC 8/100; LNG 10/100
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	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