UNITED KINGDOM - NOVEMBER 22: Depo-Provera contains a hormone similar to the body�s natural progesterone. Like other hormonal birth control methods, including the Pill, Depo-Provera causes a resting state in the ovaries, preventing an egg from being released each month so that a woman cannot become pregnant. It is administered by injection every three months. These examples were prepared by Upjohn Ltd, in Crawley, Sussex. (Photo by SSPL/Getty Images)
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