A monthly injection that combines estrogen with progestin to reduce irregular bleeding, Cyclo-Provera , may be available in the next few years. The hormone keeps the ovaries from releasing eggs. It also thickens the cervical mucus. This keeps sperm from joining with an egg. Of every 1,000 women who use Depo-Provera, only three will become pregnant during the first year.
Injections provide no protection against sexually transmitted infections.
Most women can use injections safely. After taking your medical history and giving you a physical exam, the clinician will inject the hormone into your buttock or arm. Protection against pregnancy begins within 24 hours if you get the injection during the first five days of your period. Do not have an injection if there is a chance that you are pregnant. Be sure to tell your clinician if you think there is any chance that you are.