<unk>  is used in hormonal contraception in form of the<unk>  contraceptive implant and the contraceptive vaginal ring (brand names NuvaRing, Circlet), the latter in combination with ethinylestradiol.<unk>  birth control implants are a type of long-acting reversible contraception, which has been shown to be one of the most effective form of birth control. The failure rate of the implants is 0.05% for both perfect use and typical use because the method requires no user action after placement. Studies of one type, which include over 2,467 women-years of exposure, found no pregnancies. Other studies have found some failures with this method, some attributed to failures of the method itself and others to improper placement, drug interactions, or conception prior to method insertion. In comparison, tubal sterilization has a failure rate of 0.5% and IUDs have a failure rate of 0.2–0.8%. A single implant is approved for three years with data showing effectiveness for five years.
Etonogestrel
Levonorgestrel
Gestodene
Desogestrel
Norgestrel
Chloroethynylnorgestrel
5α-Dihydrolevonorgestrel
Hexestrol