Understanding Contraceptives: Depo-Provera
Depo-Provera is an injectable form of progesterone. This article discusses what it is, how it works, side effects, and other considerations.
Depo-Provera is an injectable form of the hormone progestin (medroxyprogesterone acetate), and has been in use as a contraceptive since 1992, when the FDA first approved its use.
How It Works
Progestin is a synthetic form of the hormone progesterone, which is made by the ovaries during the second half of the menstrual cycle, and is also released during pregnancy. Progesterone has several effects, including changing the lining of the uterus (endometrium) to make it more difficult for a fertilized egg to implant, and causing the mucous in the cervix to thicken (which helps prevent the entrance of sperm). It also suppresses ovulation, or the maturing and releasing of eggs. Without ovulation, pregnancy cannot occur. Depo-Provera is degraded slowly over several months after being injected, and is considered most appropriate for use by women who want to delay pregnancy for at least one year.
When Depo-Provera is taken as recommended, it is 99.7 % effective at preventing pregnancy. One advantage to Depo-Provera is that a woman does not need to remember to take a daily pill or to use a barrier method, and this keeps the failure rate when on it very low. It is more effective than either the pill, condoms, an IUD, or the diaphragm. But it cannot protect a woman against sexually transmitted diseases such as chlamydia or HIV.
How It Is Taken
Depo-Provera is administered as a shot in a medical provider’s office once every three months and is only available by prescription. The medical provider must first do a thorough physical exam, and the shot is given in the arm or buttocks muscle. The shot is given within 5 days after the beginning of a normal menstrual period (or else the woman has to use back-up contraception for several weeks). Depo-Provera is considered a reversible form of birth control and a woman needs to continue the shots every three months or she will become fertile again.
Most women on Depo-Provera notice menstruation changes during the first six months such as irregular periods or spotty periods, breakthrough bleeding (bleeding or spotting between periods), or heavier bleeding than normal. After six months to a year of taking Depo-Provera, periods may be missed or stop altogether. This is not considered harmful, and the periods start again once the Depo-Provera is stopped. Pregnancy-like symptoms such as weight gain, tender breasts, abdominal discomfort, and darkened spots on the face can occur. Dizziness, rashes, fatigue, depression, hair loss, change in sexual drive, an increased appetite, acne, and headaches are other side effects that have been noted. Most of these side effects lessen within a few months after starting Depo-Provera.
Some concerns have been raised that the lowered estrogen levels while on Depo-Provera can lead to decreased bone density, and follow up studies are being done to address this issue.
If a woman has diabetes, she should let her medical provider know before starting Depo-Provera, since Depo-Provera may affect insulin levels slightly.
It can take up to a full year to become pregnant after having an injection, and the hormone effects will stay in a woman’s system until they are cleared out. If a woman has liver disease, a history of stroke, breast cancer, a history of strokes, unexplained uterine/vaginal bleeding, or she suspects pregnancy, she should not take Depo-Provera. It is important for a woman to notify her health care provider immediately if she experiences chest pain, shortness of breath, heavy vaginal bleeding, a severe headache, or unusual pain or swelling in her legs while on Depo-Provera.
Depo-Provera can be taken by women who are breastfeeding, since the hormone progesterone does not interfere with the production or quality of breast milk, and it has no known ill effects on the nursing baby.
Depo-Provera has other benefits that include the fact that it contains no estrogen (so there is no risk related to estrogen use), and in some women reduces cramping, and reduces anemia (because periods are lighter). It can also help protect against endometrial and ovarian cancer.
Women today have more options than ever before in their choice of contraceptive. Depo-Provera is an injectable, longer lasting form of hormone birth control that offers the advantage of freedom from a daily pill or barrier method, yet it is reversible once it is discontinued. A woman should weigh factors such as whether she wants to become pregnant quickly after discontinuing birth control (it can take up to 18 months for pregnancy to occur after discontinuing Depo-Provera), convenience, her risk of side effects, cost, and other factors and discuss them with her medical care provider before making a decision.