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depo provera

Contraceptive Injectables

Depo Provera

What is Depo Provera?

Depo Provera and and the lower dose Depo-subQ Provera 104 is birth control drug administered by injection. Depo Provera consists of a synthetic hormone given at a doctors office or clinic. There are several types of birth control drugs that can be given by injection, but currently Depo Provera is the only one available in the United States. The drug remains effective for three months at a time.

How does Depo Provera work?

Depo Provera is a synthetic female hormone (depot medroxyprogesterone). It is believed to work by multiple mechanisms, although the primary mechanism is the prevention of ovulation. No egg is released so sperm cannot fertilize it. Depo Provera may also prevent fertilization by changing the consistency of natural secretions in the vagina, making it harder for the sperm to reach the egg. Some women contuniue to ovulate while on Depo Provera. When this occurs, the drug works by making it harder for the embryo to implant in the womb by keeping the lining of the uterus thin.

Its not hard to figure out which mechanism is at work. Generally, if a woman is having no periods she is not ovulating, but if she is having periods while on Depo Provera then she is ovulating.

How effective is Depo Provera?


Annual Failure Rate

Injectables have an overall annual failure rate of 3.2%. That means each year less than 1 in 30 users experience an unplanned pregnancy. Injectables have a lower annual failure rate of 2.7% for married couples, but a higher rate of 6.5% for cohabiting couples. Depo Provera is also less effective for teens and couples in their early twenties. Compared to other methods, injectables are a highly effective method of birth control.

Side-effects and health risks of Depo Provera

Depo Provera causes bone density loss in about half of adolescent users. Lower body mass, lower calcium intake, and greater alcohol use seem to be associated with greater loss.

Common side-effects and health risks are lised below, but not all are provided due to space limitations. One important concern for Depo Provera users is that side-effects are not immediately reversible. Problems may continue from 3 to 12 months after the last injection.

Problems caused by Depo Provera
Severe allergeic reaction
Loss of bone density
Weight gain
Fatigue and tiredness
Insulin resistance
High blood pressure
Acne and/or oily skin
High cholesterol
Irregular menstrual bleeding
Lack of menstrual bleeding
Continuous menstrual bleeding
Breast tenderness
Heart attack (rare)
Breast tumor growth (rare)

Considerations for Christians

Most medical organizations define pregnancy as beginning with implantation. By this definition anything that prevents implantation is still considered contraception, including Depo Provera. However, life begins when fertilization occurs, so many Christians would consider Depo Provera a possible abortifacient — a drug that causes a very early abortion. Although it is thought that Depo Provera is more likely to prevent ovulation, there still exists a real risk to pre-born life.

Related Links

Source for Failure Rates: N Ranjit, A Bankole, JE Darroch, S Singh, "Contraceptive Failure in the First Two Years of Use: Differences Across Socioeconomic Subgroups," Family Planning Perspectives, 2001, 33(1):19-27. (pdf)

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