The birth control shot (sometimes called Depo-Provera, the Depo shot, or DMPA) contains the hormone progestin. Progestin stops you from getting pregnant by preventing ovulation. When there’s no egg in the tube, pregnancy can’t happen. It also works by making cervical mucus thicker. When the mucus on the cervix is thicker, the sperm can’t get through. And when the sperm and the egg can’t get together, pregnancy can’t happen.