Depo-Provera is an injection of a hormone called progestin. It is similar to the body's natural hormone progesterone. Depo Provera injections prevent a woman's ovaries from releasing eggs. Depo-Provera is more than 99 percent effective and is generally considered the most effective reversible method of birth control. Used alone, it doesn't protect you against sexually transmitted infections.

How Depo-Provera is Administered

Injections of Depo-Provera are given every 12 weeks to prevent pregnancy. You can get these shots from a doctor or clinic. Women who have a Depo-Provera injection must not be pregnant at the time of the first injection. To avoid this, it is best to have the first injection:

• in the first five days of your menstrual period
• within five days of an abortion
• within five days of giving birth

If you do not have the injection at one of these times, you should use another method of birth control as back-up for two full weeks so you don't get pregnant. Depo-Provera is safe when you are breast-feeding.

Most women have some irregularities in the menstrual bleeding after starting Depo- Provera injections. Periods often stop altogether after six to twelve months using Depo-Provera . The effects of Depo-Provera can last for some time after you choose to stop the injections, as it takes some time for the hormone to clear out of your system. While most women get their periods within 6 months of their last injection, some women take up to two years to get their periods back.

Advantages

• women who have health conditions that prevent them from taking birth control pills can often take Depo-Provera
• very effective at preventing pregnancy
• you don't have to interrupt sex
• the woman controls this method of birth control
• you don't have to remember a daily pill
• very safe

Disadvantages

• you are not protected against sexually transmitted infections
• you may have irregular menstrual bleeding or more frequent bleeding
• you must return to the clinic/doctor every 12 weeks for your injection
• you may experience side effects (see below)
• women with some medical conditions cannot use Depo-Provera (Women should not use this method if they have abnormal vaginal bleeding, liver diseases such as jaundice or hepatitis, or breast cancer.)
• while unlikely, you may not be able to get pregnant for up to two years after using Depo-Provera

Side Effects

Some women who use Depo-Provera experience side effects. If these side effects interfere with your life you may wish to consider other methods of birth control. Women on Depo-Provera may experience:

• irregular menstrual bleeding or more frequent periods (Most women have no periods at all after 6-12 months.)
• weight gain of more than two pounds each year when Depo-Provera is used (This weight gain may continue for a number of months after you stop using Depo-Provera.)
• headaches
• breast tenderness
• bloating
• depression
• unwanted hair or hair loss

Large studies have not shown any link between Depo-Provera use and breast cancer but research is still being done in this area. Researchers are also studying whether Depo-Provera can decrease a woman's bone mineral density increasing her risk of osteoporosis.