Injected Contraception
Injected contraceptives help fill the needs of women who are able to take hormonal contraceptives but have difficulty complying with daily pills. Injected progestins have been the standard form, but they can have severe effects on the menstrual cycle. More recently, combination injections of estrogen and progestins have been developed that are effective, have fewer side effects than progestin injections, and may even have health benefits.
Injected Progestins
Injected progestins, particularly depo-medroxyprogesterone acetate or DMPA (Depo-Provera), are currently the standard injected contraceptive and are very effective. Depo-Provera uses a progestin called medroxyprogesterone. Like other progestin contraceptives, Depo-Provera prevents pregnancy by halting ovulation, thickening the cervical mucus, and stopping the implantation of fertilized eggs in the uterine lining.
Administering Injections. The typical procedures for progestin injections are as follows:
- A physical examination is necessary before beginning the injections.
- It is injected into a muscle in the patients arm or buttock, and during months between injections, the hormone slowly diffuses out of the muscle into the bloodstream.
- Depo-Provera requires an injection by the physician every three months. Another injected progesterone (Noristerat) needs to be injected every two months.
- If more than two weeks pass beyond the regular injection schedules, the woman should have a pregnancy test before taking the next one.
Candidacy for Injected Progestins
Depo-Provera is a good choice for many women who want to delay pregnancy for several years but hope to bear children later on. It is safe for many women who are not candidates for OCs, including smokers over 35, and for those who have the following conditions:
- Risk for blood clots or stroke.
- Migraines.
- Diabetes.
- Systemic lupus.
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| Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder which may affect many organ systems including the skin, joints and internal organs. The disease may be mild or severe and life-threatening. African-Americans and Asians are disproportionately affected. |
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It may actually reduce the frequency of crises in sickle cell patients, and reduce seizures in women with epilepsy.
Depo-Provera is not given to women with the following conditions:
- Liver disease.
- Unexplained vaginal bleeding.
- Pregnancy.
- Women who are breastfeeding for the first six weeks after delivery.
- Women at risk for osteoporosis.
Because of the long lag time between ending treatments and restoration of fertility, Depo-Provera is not recommended for women who are thinking of becoming pregnant within two years.
Advantages of Injected Progestins
The advantages of Depo-Provera are as follows:
- Progesterone injections provide highly effective reversible protection against pregnancy without placing heavy demands on the users time or memory.
- They also may protect against uterine and ovarian cancer and do not pose any risk for breast cancer.
- DMPA is also useful for painful periods, heavy bleeding (including heavy bleeding caused by fibroids), premenstrual syndrome, and endometriosis.
- Depo-Provera does not appear to cause weight gain as other hormonal agents may.
Disadvantages and Complications of Injected Progestins
Disadvantages are as follows:
- Side effects of any progestin-containing contraceptive. For example, about 60% of users gain weight during long-term use. For these and other reasons, 70% of users stop the injections within a year.
- Most users of Depo-Provera stop menstruating altogether after a year. Women who eventually want to have children should be aware that Depo-Provera can cause persistent infertility for up to 22 months after the last injection, although the average is 10 months. This is significantly longer than restoration of fertility after the removal of the Norplant implant.
- Depo-Provera has been associated with a higher incidence of depression, although it is unclear whether the contraception was really the cause.
- Depo-Provera may cause loss of bone density. It appears to be reversible when the drug is stopped.
- The injections do not provide protection against sexually transmitted diseases.
- Of some concern was a 2002 study that found changes in the arteries of long-time users, suggesting a risk for future heart disease. More research is warranted.
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