A randomized, double-blind, noninferiority study to compare two regimens of levonorgestrel for emergency contraception in Nigeria

BACKGROUND:Unplanned pregnancies are common in Nigeria. Much of the unplanned pregnancies is due to low contraceptive prevalence and high contraceptive user failure rates. High user failure rates suggest the important role of emergency contraception to prevent unplanned pregnancy. STUDY DESIGN:Randomized, controlled, double-blind, multicenter, noninferiority trial comparing efficacy and side effects of two emergency contraceptive regimens up to 5 days after unprotected intercourse among 3022 Nigerian women: levonorgestrel administered in two doses of 0.75 mg given 12 h apart and levonorgestrel administered in a single dose of 1.5 mg. RESULTS:Efficacy was similar between the treatment groups; post-treatment pregnancy proportions were 0.57% in the two-dose regimen vs. 0.64% in the single-dose regimen (risk difference 0.07% (95% CI -0.50 to 0.64). The majority of women menstruated the first day of expected menses and the groups did not differ regarding reported side effects. CONCLUSIONS:This study shows the simplified emergency contraceptive regimen of single-dose levonorgestrel is not inferior in efficacy to the two-dose regimen among Nigerian women.