The type of shot most used is called Depo-Provera. It is a hormone, much like the progesterone a woman produces during the last two weeks of each monthly cycle. Depo-Provera or progesterone stops the woman's ovaries from releasing an egg and has other contraceptive effects. Among typical couples who initiate use of Depo-Provera, about three in 1,000 women will experience an accidental pregnancy in the first year. For the most effective protection against sexually transmitted infections, use condoms as well. Complete information about this contraceptive is available through a family planning clinic, local health department, or clinician.

• Nothing needs to be taken daily or at the time of sexual intercourse.
• The shot is extremely effective. If women receive their injections on time (every 14 weeks or three months), only three women in 1,000 become pregnant in the course of an entire year.
• Women lose less blood during menstruation when they are using Depo-Provera and have less menstrual cramps.
• Privacy is a major advantage. No one has to know a woman is using this method.
• Nursing mothers can receive Depo-Provera injections: it is best to receive after the baby is six weeks old.
• It is okay for a woman to start another contraceptive method if it is less than 13 weeks since the last shot.
• The Depo-Provera shot may lead to improvement in PMS (premenstrual symptoms), depression or symptoms from endometriosis.

• Depo-Provera injections can lead to very irregular periods. If a woman's bleeding pattern is bothersome, there are medications which can be given to help have a more acceptable pattern of bleeding.
• Some women gain weight. To avoid weight gain, women should watch their calorie intake and get lots of exercise.
• A woman has to return every three months for her injection.
• Depression and premenstrual symptoms may become worse.
• Depo-Provera does not protect you from HIV infection or other STDs. Use condoms to reduce risk.
• It may be a number of months before a woman's periods return to normal after her last shot.
• Depo-Provera may cause bone loss, although this is not certain. Women should get regular exercise and consider taking extra calcium to protect their bones from osteoporosis.
• Some women are allergic to Depo-Provera.

You can get Depo-Provera injections from your clinician, health department, or family planning clinic. Most clinics provide the first shot when a woman is on her period or within seven days of the start of the period.

Be sure to use condoms or another method for added protection. Also, emergency contraception is an option that can prevent pregnancy after unprotected sex—but it does not prevent against sexually transmitted diseases.