Long-Acting Hormonal Methods

Depo-Provera Injectable Contraceptive

Average Annual Failure Rate: 3%

Depo-Provera (DMPA), and the lower dose Depo-subQ Provera 104, are highly-effective birth control injections administered by a doctor every three months. Also called "the Shot," Depo-Provera consists of a synthetic female hormone, or progestin. Unlike combined oral contraceptive pills, Depo-Provera is estrogen-free, which means that it is safer and has fewer serious side-effects than other hormonal methods.

How Depo-Provera Contraceptive Works

Depo-Provera and Depo-subQ Provera 104 work as birth control in the same way as other progestin-only (estrogen-free) hormonal contraceptives, like the mini-pill. The drug prevents ovulation so that no sperm can fertilize an egg, and it thins the lining of the uterus so that an embryo cannot implant as an additional post-fertilization mechanism. Although most women do not ovulate while taking Depo-Provera, thirty percent have regular cycles, which indicates continued ovulation. For women who are ovulating, Depo-Provera is less effective.

Side-Effects of Depo-Provera Contraceptive Injection

During the first year of use about a quarter of women fail to menstruate altogether, and lack of periods increases with continued Depo-Provera use. Common side-effects include headache, hair loss, nervousness, weight gain, and menstrual irregularities. Users of Depo-Provera may not have periods for a full year. This can be unsettling to women who wonder if they may be pregnant, as normal Depo-Provera side-effects may mimic pregnancy symptoms. Other possible adverse effects include dizziness, allergy, ovarian cysts, and continuous menstruation that can last for months.

Health Risks of Depo-Provera Contraceptive Injection

Adolescent users especially, as well as adults, have been found to experience a significant loss of bone density, leading to increased risk of osteoporosis. This loss of bone density does not appear to be reversible. The manufacturer and the US FDA recommend that Depo-Provera not be used for more than two years due to concerns over bone loss.

In animals, Depo-Provera was found to suppress the immune system. This may be one reason why Depo-Provera seems to increase the risk of acquiring HIV and other STDs from an infected partner. The effects of Depo-Provera on breast cancer are still not known, but abnormal Pap smears are more common among users. Similar progestins are known to cause birth defects. Miscarriage and infant mortality are increased for children whose mothers were taking Depo-Provera when they became pregnant.

Although only a small percentage of women have an allergic reaction, this situation can be life-threatening. Anaphylaxis and anaphylactoid reactions have been reported with the use of Depo-Provera Contraceptive Injection and require emergency medical treatment. The most serious problem is that there is no easy way to get the drug out of a woman's system, and she may suffer with allergic symptoms for the next year.

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