Birth control shots deliver synthetic hormones via an injection and are reversible methods of prescription birth control. Depending on the brand, pregnancy protection can range 30 days to 14 weeks. Depo Provera, as well as its newer version, the Depo-subQ Provera 104 Injection, is a progestin-only injection. Noristerat is another progestin contraceptive injection but is not available in the US. Combined contraceptive injections are birth control shots that contain both estrogen and progestin.
Depo Provera Injection © 2007 Dawn Stacey licensed to About.com, Inc
The shot, also known as DMPA or by its progestin, medroxyprogesterone is an injectable form of progestin (one of the same synthetic hormones found in the pill). This method works by thickening cervical mucus and suppressing ovulation. It must be given every 3 months (12 weeks) and will only provide optimal pregnancy protection for that amount of time. There are two versions available - the Depo Provera shot and the newer version, Depo-subQ Provera injection.
Combined Contraceptive Injection Photo Courtesy of P. Cosio
Similar to combination birth control pills
, combined contraceptive injections contain a combination of synthetic estrogen and progestin. The hormones are injected into the muscle of the upper arm, thigh, or buttocks and must be injected every 28 to 30 days (once every month). Monthly contraceptive injections prevent pregnancy for about 30 days. Lunelle is a monthly injection that contains the synthetic hormones estradiol cypionate and medroxyprogesterone. This method became available in the United States in 2000 but was recalled in 2002. This birth control shot is now sold under the name Cyclofem. Mesigyna is another type of combined contraceptive injection; both of these brands are found mostly in Latin America and Asia.
Noristerat Injection Photo Courtesy of M. Donohue
The noristerat injection is a reversible method of prescription birth control method. It is not available in the United States but is common in the United Kingdom, Europe, Africa, and Central America. This contraceptive injection contains the synthetic progestin norethisterone enantate. The noristerat injection is a depot contraceptive that is given into the muscle of the buttock. It continuously releases its progestin into the bloodstream over a period of eight weeks, therby providing pregnancy protection for up to two months.