Depo Provera
General Considerations
Medroxyprogesterone acetate, known as Depo-Provera, is an injectable contraceptive derived from a natural hormone, progesterone. It was synthesized in 1954 and has been in use since 1960. It is estimated that over 30 million women have used this method of contraception at some point in their life in over 100 countries, including the United States.
Since April 1997, Depo-Provera has been officially approved, in Canada, for contraceptive use.
How it Works
Injection of the product into a muscle causes a rapid increase of progesterone levels in the blood. This concentration in the blood is enough to provide contraception for 3 months.
The compound acts in different ways:
- It prevents ovulation.
- It makes the lining of the uterus unable to receive a fertilized egg.
- It alters the cervical mucous.
Effectiveness
It is 99.7% effective, which is comparable to tubal ligation. In order to be effective, injections must be administered regularly every 11 to 13 weeks.
Indications
Depo-Provera is a good option, especially in the following situations:
- Repeated failure of other methods of contraception
- Inability to tolerate contraceptive pills or contraindications for pill use
- Frequently forgetten pills
- Smoker over the age of 35
- Increased risk of infection with an IUD
- When amenorrhea (absence of periods) can relieve menstrual pain or premenstrual tension
- When amenorrhea offers medical or personal hygiene advantages
- Long-term use of medications that reduce the effectiveness of contraceptive pills (e.g. some medications for epilepsy)
- Endometriosis
CONTRAINDICATIONS
There are two absolute contraindications for the use of Depo-Provera. They are:
•Pregnancy
•Unexplained uterine bleeding
Route of Administration
For contraceptive use, Depo-Provera comes in a 1 ml vial containing 150 mg of the medication which is injected into the arm or buttock every 11 to 13 weeks.
The first injection must be administered in the first 5 days of menstruation, in order to be effective immediately. If the injection is administered after this time, you must wait a week in order for the protection to be effective.
If an injection is administered more than 14 weeks after the previous injection, you must wait a week before protection is again effective and use another method of contraception during this time. If there were unprotected sexual relations after the 14th week, one must ensure that there is no pregnancy before receiving the next injection of Depoprovera. The injection may be administered by a doctor or a nurse.
Cost
An injection costs $32 to $45; however, Depo-Provera is covered by Quebec's prescription drug insurance plan and private insurance.
Side Effects
The most common side effect is breakthrough bleeding (irregular, unpredictable bleeding that is rarely heavy). It usually disappears after a few months of use, when amenorrhea or an absence of periods begins.
The method is effective, whether there is bleeding or not. Menstrual cycles will return within 6 months of the final injection in most cases. However, in some cases, periods may be absent for 12 to 18 months.
Nevertheless, another effective method of contraception should be used from the end of the 14th week following the injection, if pregnancy is not desired
Weight gain is another common side effect (average of 2.5 kg for the first year of use); it results from stimulation of the appetite. However, weight loss has been seen in 20% of women.
The medication may cause other side effects similar to those seen with oral contraceptives: headaches, abdominal pain or discomfort, fatigue, nausea, decrease in sex drive, breast tenderness, mood swings, and depression.
There have been no studies linking this method of contraception and breast cancer in women. Moreover, some studies associate use of Depo-Provera with a major decrease (80%) in the risk of cancer of the endometrium (inner lining of the uterus) and a small decrease in the risk of ovarian cancer.
Some users may experience bone loss. To avoid this side effect, physical activity, the consumption of dairy products, and quitting smoking are recommended. Please note that in a majority of women, this bone loss is completely reversible after 2 years of discontinuing the Depo-Provera injections.
The medication does not alter blood lipid levels (cholesterol); it does not have any significant effect on blood pressure or on the risk of cardiovascular disease.
Lastly, there is no benefit to limiting the number of years of use of this method if it proves fully satisfactory.
Future Fertility
Fertility generally returns 6 to 9 months after the last injection and coincides with a return to a normal menstrual cycle.
Sometimes, the delay may be as long as 18 months. After this time, fertility is not reduced, regardless of the number of years of use. Moreover, this method of birth control has no impact on the risk of miscarriage or congenital defects.
Conclusion
Depo-Provera is an effective, safe method of contraception that may suit many women. It is a good choice for all women with contraindications or intolerance or who simply have not been happy with other methods.