WHO 1999

Methods	Multinational RCT. Randomisation sequence was generated centrally at the WHO and women randomised to 3 groups within centres. Sequentially‐numbered bottles, each containing 3 pills were given to women at the centre. Each bottle contained the active and placebo pills accordingly. However, 200 mg pills were slightly larger and, therefore, not all pills were identical. Power calculation was made
Participants	1717 women attending family planning clinics in 11 centres in 6 countries Included women with regular menstrual cycles, within 120 h of a single act of unprotected intercourse and who were willing to avoid intercourse for the rest of the current cycle Excluded women who were breastfeeding, with uncertain date of last menstrual period, use of hormonal contraception in the current cycle and those with a contraindication to Mife use. 1684 women included in the final analysis
Interventions	Mife 600 mg vs Mife 50 mg vs Mife 10 mg. All taken orally as a single dose at the time of enrolment
Outcomes	Observed number of pregnancies, side effects and changes in menstrual pattern
Notes	Loss to follow‐up: 32/1717 (1.9%) Exclusion: 1 woman was excluded because she was pregnant at the time of enrolment. There were 15 protocol violations (cycle length outside admissible range, treatment after 120 h, further use of EC in the same cycle) but these were included in the analysis Observed pregnancy/expected pregnancy/total number of women: Mife 600 mg 7/45/559; Mife 50 mg 6/43/560; Mife 10 mg 7/48/565 2 ectopic pregnancies in Mife 50 mg group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"We used a computer generated randomisation sequence developed by WHO staff to assign participants to treatment groups within centres. Each centre received assignments by randomly permuted blocks with a fixed block size of nine."
Allocation concealment (selection bias)	Low risk	"The manufacturer supplied sequentially numbered bottles of pills for each participating centre, according to the randomisation sequence. We attempted to maintain allocation concealment by having three pills in each bottle; two 5 mg tablets plus one placebo tablet for the 10 mg dose; one 50 mg tablet plus two placebo tablets for the 50 mg dose; and three 200 mg tablets for the 600 mg dose. Each bottle was sealed and labelled sequentially with the number of the centre, participant number, and expiry date."
Blinding (performance bias and detection bias) All outcomes	Low risk	"Each pill bottle contained three white tablets. The 200 mg tablets were somewhat larger than the 50 mg and 5 mg tablets or placebos. Clinicians and participants were not told the composition of the three pills."
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Allocations were by intention to treat."
Selective reporting (reporting bias)	Low risk	Primary and secondary outcomes reported (unintended confirmed pregnancy, side‐effects and delay in the onset of next menses)
Other bias	Low risk	None detected