Etonogestrel is a progestin

Progestin

A progestin is a synthetic progestogen that has progestinic effects similar to progesterone. The two most common uses of progestins are for hormonal contraception , and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy...

 used in hormonal contraceptives, most notably the subdermal implant Implanon

Implanon

Implanon, made by Organon International, is a single-rod long acting reversible hormonal contraceptive subdermal implant that is inserted just under the skin of a woman's upper arm. The 4 cm by 2 mm Implanon rod contains 68 milligrams of etonogestrel which is released over a three year...

 and the contraceptive vaginal ring NuvaRing

NuvaRing

NuvaRing is the trade name for a combined hormonal contraceptive vaginal ring manufactured by Merck that is available by prescription...

.

Etonogestrel is the active metabolite of the inactive prodrug desogestrel, one of two third-generation progestins found in some epidemiological studies of combined oral contraceptive pills to be associated with a higher risk of venous thrombosis than combined oral contraceptive pills containing certain second-generation progestins. Because hormones are released continuously from NuvaRing, peak and total estrogen and progestin doses are significantly lower than with combined oral contraceptives, although it is not known whether this lowers the risk of blood clots.