The Depo-Provera shot, commonly known as the Depo shot, is highly effective as a birth control method. With perfect use—meaning getting the injection every 3 months exactly on schedule—its effectiveness is about 99% at preventing pregnancy. Typical use, which accounts for occasional delays or missed shots, results in about 94% to 97% effectiveness. This means that with typical use, about 3 to 6 women out of 100 may become pregnant during one year of using the shot. The injection works by stopping ovulation and changing the uterine lining to prevent pregnancy. It must be given every 13 weeks (around 3 months) to maintain effectiveness. If the injection is delayed more than 2 weeks beyond the scheduled time, the risk of pregnancy increases, and another form of contraception should be used to be safe.
In summary, the Depo shot is one of the most reliable reversible contraception methods when used correctly and on time, though typical real-world use can slightly reduce its effectiveness.
