A randomized trial of mifepristone (10 mg) and levonorgestrel for emergency contraception.

OBJECTIVE: To compare the efficacy, patient acceptability and adverse effects of low-dose mifepristone (10 mg) with the levonorgestrel regimen (2 doses of 750 microg given 12 hours apart) for emergency contraception.

METHODS: This randomized controlled trial compared mifepristone (10 mg) to levonorgestrel (2 doses of 750 microg given 12 hours apart) in the context of emergency contraception within 120 hours of unprotected intercourse. The primary outcome measure was unintended pregnancy. Secondary outcomes included adverse effects experienced by women, acceptability of the method of emergency contraception used, and the timing of the first menstrual cycle after treatment.

RESULTS: The total number of women recruited was 2,065. The crude pregnancy rates were 1.3% and 2.0% for mifepristone and levonorgestrel (P = .46), with 77% and 64% of expected pregnancies prevented, respectively. Women receiving mifepristone were more likely to have a delayed onset of the subsequent menstrual cycle after treatment (P < .001), whereas those having levonorgestrel were more likely to have an early onset of the subsequent menstrual cycle (P < .001). Acceptability levels were high for both methods, with 94% of women receiving mifepristone and 91% receiving levonorgestrel expressing satisfaction. There was no difference in adverse effects (nausea, vomiting, breast tenderness, abdominal pain, lethargy, headache, hot flushes, and dizziness) experienced by women in the 2 groups.

CONCLUSION: This study suggests that a small dose of mifepristone is not less effective than levonorgestrel for emergency contraception. Both regimens were highly acceptable to women.