Depo-Provera is a form of contraception. It is a drug very similar to progesterone, a hormone normally produced by the ovaries every month as part of the menstrual cycle. Depo-Provera is an injectable medicine that prevents pregnancy for up to 3 months with each injection.
Depo-Provera prevents pregnancy by preventing ovulation (the release of an egg from the ovary). If an egg is not released, pregnancy is unlikely. Depo-Provera is given as 1 shot in the buttock or upper arm. The first shot should be given within 5 days after the beginning of a normal menstrual period, and shots should be repeated every 3 months.