Hormonal birth control methods work by preventing ovulation—in other words, by keeping the ovaries from releasing an egg. When someone starts a method for the first time, we don’t know for sure whether or not she has already ovulated, so we recommend she use back-up birth control for the first week. If she has already ovulated and the egg is still in the uterine tubes, there could be a high risk of pregnancy from unprotected sex.
Unfortunately, that means you’re not protected immediately on the shot. Take Plan B if the unprotected sex occurred less than five days ago to reduce your risk of pregnancy. If it’s too late for Plan B, consider taking a pregnancy test two weeks after the unprotected sex. Teen Clinic offers free or low-cost pregnancy tests! Call us at 303-442-5160 to make an appointment for one.
In the future, getting your shots on time will keep you 99% protected from pregnancy, even the first week after the shot. If you get a shot late, however, you’ll need backup birth control again. Talk to your medical provider to make sure you understand your method—it’s an important part of being sexually active!