Birth Control Hormonal Methods (cont.)
Injections and Combination Injections
An injection of synthetic hormone medroxyprogesterone acetate (DMPA, Depo-Provera) can be given every 3 months to stop ovulation. The injection is given at a doctor's office. After injection, the medication is active within 24 hours and lasts for 3 months. It prevents the ovaries from releasing eggs.
- How effective: DMPA is an extremely effective contraceptive option. Most other medications or a woman's weight do not change its effectiveness. Within the first year of use, the failure rate is 0.3%.
- Advantages: DMPA does not produce the serious side effects that estrogen does, such as blood clotting. It lowers the risk for certain endometrial and ovarian cancers. Irregular periods may become regular.
- Disadvantages: Some women may not have a period within the first year. Irregular bleeding can be treated by giving the next dose earlier or by temporarily adding a low-dose estrogen. Because DMPA lasts in the body for several months in women who have used it on a long-term basis, it can delay the return to fertility. About 70% of former users desiring pregnancy conceive within 12 months, and 90% of former users conceive within 24 months. Other side effects, such as weight gain, depression, and menstrual irregularities, may continue for as long as 1 year after the last injection. Recent studies suggest a possible link between DMPA and bone density loss. This method does not protect against STDs.
Medically reviewed by Steven Nelson, MD; Board Certified Obstetrics and Gynecology
Medically Reviewed by a Doctor on 8/5/2014
Francisco Talavera, PharmD, PhD
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