Depo-Provera is a contraceptive injection containing progestogen that prevents pregnancy by stopping the ovaries from releasing an egg each month and making changes to the lining of the uterus. Although Depo-Provera is highly effective, with a typical effectiveness rate of 97% and a perfect use rate of more than 99%, there is still a small chance of getting pregnant while using it. According to a review of contraceptive failures among women using Depo-Provera, there were 402 reports of pregnancy from 1994 through 1998, with a crude rate of reported pregnancies of 0.42 pregnancies per 1000 women using Depo-Provera each year. Although pregnancy during Depo-Provera use is rare, it does occur, and these pregnancies are frequently unrecognized until beyond the first trimester. If you get pregnant while using Depo-Provera and decide to continue with your pregnancy, there is no additional risk of damage to the baby. However, getting Depo-Provera while pregnant can lead to low birth weight. If you are planning a pregnancy soon, it may be best not to use Depo-Provera. If you miss a dose of the birth control shot or if it’s late, you can become pregnant.