Two low-dose levonorgestrel intrauterine contraceptive systems: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of two low-dose levonorgestrel intrauterine contraceptive systems. METHODS: Nulliparous and parous women aged 18235 years with regular menstrual cycles (21235 days) requesting contraception were randomized to 3 years of treatment with one of two levonorgestrel intrauterine contraceptive systems: 13.5 mg total content or 19.5 mg total content. The primary outcome was the pregnancy rate calculated as the Pearl Index. RESULTS: Overall 1432 and 1452 women in the 13.5 mg intrauterine contraceptive system and 19.5 mg intrauterine contraceptive system groups respectively had a placement attempted and were included in the full analysis set to evaluate efficacy and safety. Mean (standard deviation) age was 27.1 (4.8) years; 39.2% were nulliparous. Over the 3-year study period 0.33 pregnancies per 100 women years (95% confidence interval [CI] 0.16-0.60) were observed with the 13.5 mg intrauterine contraceptive system compared with 0.31 per 100 women-years (95% CI 0.15-0.57) with the 19.5 mg intrauterine contraceptive system. Kaplan-Meier estimates for that period were 0.009 and 0.010 respectively. At least partial expulsions occurred in 4.56% and 3.58% and discontinuation rates resulting from a reported adverse event occurred in 21.9% and 19.1% respectively. Ten of the 20 pregnancies were ectopic. Serious adverse events included six cases of pelvic inflammatory disease and one partial uterine perforation. CONCLUSIONS: Both lower-dose levonorgestrel intrauterine contraceptive systems were highly effective for 3 years of use and generally well tolerated.