von Hertzen 2002

Methods	Randomised, double‐blind, multicentre trial. Random number generation done centrally, double‐blinded by use of identical placebos. Allocation concealment achieved by sealed, sequentially numbered, treatment packs
Participants	4136 healthy women recruited in the study from 15 family planning clinics in 10 countries Included women with regular menstrual periods, aged 14‐52 years, who had attended the clinic within 120 h of a single act of unprotected intercourse Excluded women who were breastfeeding, on hormonal contraception in the current cycle and those with uncertain dates of last menstrual period
Interventions	Mife 10 mg, single dose vs LNG 1.5 mg, single dose vs LNG 0.75 mg, 2 doses, 12 h apart, orally
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Observed pregnancy/expected pregnancy/total number of women: Mife 10 mg 21/108/1359; single‐dose LNG 20/111/1356; split‐dose LNG 24/106/1356 (1 ectopic pregnancy) Lost to follow‐up: Mife 10 mg 20/1380; single‐dose LNG 22/1379; split‐dose LNG 19/1377 ITT: 4,071 into efficacy analysis, 4,084 into safety analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"We used a computer‐generated randomization sequence developed by WHO to assign participants in each centre to one of three treatment groups: single dose mifepristone; single dose levonorgestrel; or two dose levonorgestrel. Each centre received assignments by randomly‐permuted blocks with a fixed block size of 10."
Allocation concealment (selection bias)	Low risk	"Allocation was concealed by the use of sealed, sequentially numbered treatment packs, which were filled and labelled in accordance with the list of randomization for each centre by Labatec, Geneva, Switzerland." "only the person who prepared the random lists had access to them."
Blinding (performance bias and detection bias) All outcomes	Low risk	"women received two 5 mg tablets of mifepristone and two placebo tablets identical in appearance to mifepristone." "Clinicians, participants and investigators were unaware of drug assignments and this double‐blinding was maintained until after the final analysis; only the person who prepared the random lists had access to them."
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Analysis was by intention to treat" Loss to follow‐up was explained.
Selective reporting (reporting bias)	Low risk	Primary and secondary outcomes results reported
Other bias	Low risk	None detected