No pregnancies occurred in implant users during 229.4 women-years of follow-up, and only one pregnancy in 197.7 women-years of follow-up occurred with IUD use beyond the FDA-approved time intervals
The etonogestrel contraceptive implant and the 52-mg levonorgestrel intrauterine system (LNG-IUS) remain highly effective for an additional year beyond the FDA-approved intervals of 3 and 5 years, respectively, according to a newly published prospective study.1
In the study, implant users (n = 237) contributed 229.4 women-years of follow-up, with 123 women using the implant for 4 years and 34 using it for 5 years. No pregnancies were documented—a failure rate of 0 (one-sided 97.5% confidence interval [CI], 0–1.61) per 100 women-years.
Of 263 LNG-IUS users, 197.7 women-years of follow-up found only one pregnancy—a failure rate of 0.51 (95% CI, 0.01–2.82) per 100 women-years.
Among implant users with serum etonogestrel levels assessed, the median at 3 years of use was 188.8 pg/mL (range, 63.8–802.6 pg/mL). At 4 years, the median etonogestrel level was 177.0 pg/mL (range, 67,9–470.5 pg/mL). Etonogestrel levels did not vary by body mass index at either 3 years (P = .79) or 4 years (P = .47). These serum levels indicate that the implant contains adequate hormone for ovulation suppression at the end of both 3 and 4 years of use.