Extended Effectiveness of the Etonogestrel-Releasing Contraceptive Implant and the 20 µg Levonorgestrel-Releasing Intrauterine System for 2 Years Beyond U.S. Food and Drug Administration Product Labeling

BACKGROUND Contraceptive implants, the levonorgestrel-releasing intrauterine system (LNG IUS), and the copperbearing intrauterine device (IUD) are long-acting reversible contraceptives (LARCs) with high contraceptive effectiveness. The cumulative pregnancy rates in the first 3 years of use of LARCs is 0.9 per 100 woman-years. In comparison, the percentages of women experiencing an unintended pregnancy during the first year of typical use of short-acting methods are much higher, including for male condoms (18%), the diaphragm (18%), DepoProvera injectables (6%), and combined oral contraceptive pills or progestin-only pills (9%). The high effectiveness of LARCs is equal in women of all ages, whereas younger women using the pill, patch, or vaginal ring have a significant increase in contraceptive failure in comparison with failure rates among older women. Moreover, LARCs convey many other advantages for clients in terms of convenience, satisfaction, ease of continuation, likelihood of avoiding unintended/unwanted pregnancy, and noncontraceptive benefits. For these reasons, LARCs should also be among the readily available contraceptive choices for women, including young and nulliparous women. If their duration of effective use were to be extended, that would likely be another perceived benefit of LARCs. BRIEF DESCRIPTION OF HORMONAL LARCS Etonogestrel-Releasing Implant The etonogestrel (ENG)-releasing implant contains 68 mg ENG embedded in 1 ethylene-vinyl-acetate rod (marketed in the United States as Implanon and Nexplanon, Merck & Co., Inc., Whitehouse Station, NJ, USA). ENG is the biologically active metabolite of desogestrel used in some combined and progestogen-only contraceptive pills. The ENG-releasing implant is currently labeled for 3 years of use. The original 1-rod ENG-releasing contraceptive implant had first regulatory approvals in 1998 in Indonesia. Mechanism of action. Contraceptive implants act by binding to their receptors located in diverse target cells, which are distributed along the hypothalamicpituitary-gonadal-genital tract axis. The implant has the ability to interfere with several key processes required for gamete encounter and fertilization. The progestins work both by suppressing and altering ovulation and by thickening the cervical mucus. They also restrict or suppress the access of fertile spermatozoa to the site of fertilization.