Depo-Provera: the quarterly contraceptive

FDA Consumer, March, 1993 by Dori Stehlin

It may be the birth control compromise many woman have been looking for. Falling in between the daily effort of remembering the pill and the once-every-five-years appointment for the implant, one injection of Depo-Provera in the muscle of the arm or buttocks protects against pregnancy for three months.

The Food and Drug Administration approved Depo-Provera, manufactured by The Upjohn Co., Kalamazoo, Mich., for contraception last October. The active ingredient in Depo-Provera is a synthetic hormone similar to the natural hormone progesterone.

"I was not happy with other methods," says Becky Schroder, of Jacksonville, Fla. "I was a poor pill taker. I forgot. And I thought that barrier methods were inconvenient and messy."

Schroder, 31, started on Depo-Provera three years ago, when its use as a contraceptive was still investigational. (FDA had previously approved the drug for treating endometrial and renal cancers.)

Depo-Provera inhibits the production of another hormone, gonadotropin, which, in turn, prevents ovulation. Depo-Provera also causes changes in the lining of the uterus that make pregnancy less likely to occur.

Depo-Provera's estimated effectiveness in preventing pregnancy is 99 percent, on a par with Norplant, the contraceptive implant. Norplant contains another synthetic progestin hormone, levonorgestrel. (See "Norplant: Birth Control at Ann's Reach" in the May 1991 FDA Consumer.)

Mark Your Calendar

The amount of Depo-Provera in the bloodstream is at the highest level just after injection. Over time, the level drops and after three months, the level may no longer offer enough protection against conception.

"Go back on time for the next injection," says Ridgely Bennett, M.D., the FDA medical officer responsible for reviewing the new drug application for Depo-Provera. "That should be made abundantly clear."

He adds that if the time between injections is greater than 14 weeks, the physician should make sure the woman isn't pregnant before giving her the next injection.

Getting Started

A woman should get her first injection of Depo-Provera within five days after the start of her menstrual period. The drug is effective immediately, so no other birth control is necessary.

Because Depo-Provera is not a barrier contraceptive, however, it offers no protection against sexually transmitted diseases such as AIDS, herpes, chlamydia, and gonorrhea. For optimum protection from both disease and pregnancy, couples may choose to use both Depo-Provera and a condom.

A woman who has just had a baby-- and wants to walt before having another-- should get her shot within five days after the birth if she is not breast-feeding, and six weeks after the baby is born, if she is.

Although numerous studies by the World Health Organization have shown that Depo-Provera does not have any adverse effects on breast milk production or composition, or on the health of the nursing infant, it's best not to expose a newborn to the drug in the first six weeks, according to Philip Corfman, M.D., a supervisory medical officer in FDA's division of metabolism and endocrine drug products. "It's just a precaution," he says.

If a woman decides at the end of three months that she wants to get pregnant, she simply doesn't get the next injection. But, because the length of time between the last injection and becoming pregnant varies widely, any woman starting Depo-Provera should be sure she doesn't want to become pregnant for the next year or two, says Susan Wysocki, executive director of the National Association of Nurse Practitioners in Reproductive Health.

According to the approved physician's label, "the median time to conception for those who do conceive is 10 months following the last injection with a range of four to 31 months." Since Depo-Provera does not accumulate in the body, the return to fertility is independent of the number of injections received, but may be affected by a woman's age or weight.

A woman should not take Depo-Provera if she has acute liver disease, unexplained vaginal bleeding, breast cancer, or blood clots in the legs, lungs or eyes.

"She also shouldn't have a fear of injections," Wysocki says.

Side Effects

Change in the menstrual cycle is the most common side effect of DepoProvera. At first there may be irregular bleeding or spotting, but that usually diminishes and eventually disappears after several injections. After a year on DepoProvera, menstruation will stop completely in approximately half of the women.

Normal menstruation will usually return within a few months once the injections stop.

Women who continue to menstruate while on Depo-Provera may have decreased blood flow, which, in turn, reduces the chance of anemia. There may also be a decrease in menstrual cramps and pain, as well as ovulatory pain.

Schroder, who had very painful premenstrual symptoms before starting DepoProvera, says she thinks of these side effects as benefits.

After menstrual changes, the most common side effect is weight gain. "It's not clear whether the weight gain is due to water retention or a metabolic effect that increases appetite and body fat," says David Grimes, M.D., a professor with the department of obstetrics and gynecology at the University of Southern California School of Medicine. "But it is real, and women should know about it."