Depo-Provera News Upbeat and Troubling
Long-term hormone use in women is complicated, as the recent findings about hormone replacement therapy--namely, that it contributes to heart disease in some users--attest.
Here’s another case from the other side of a woman’s reproductive life: In a study funded by the National Institutes of Health and published this month in the journal Epidemiology, Depo-Provera, an injectable contraceptive, was found to cause significant loss of bone density, a risk factor for osteoporosis.
That’s the bad news.
The good news is that within 2 1/2 years of stopping the contraceptive, most of the women who had used Depo-Provera had bone densities similar to women who had never used it.
“Our findings certainly indicate that if you use this method, it will have some effect on bone density,” said the lead author, Delia Scholes of the Group Health Cooperative in Seattle. However, she said, “it was pretty gratifying to see steady gains in bone density once a woman stopped the contraceptive.”
Depo-Provera, produced by Pharmacia Corp., is a progesterone-only contraceptive given as a shot every three months. It stops the ovaries from releasing eggs--meaning a woman doesn’t get a period--and it thickens the cervical mucus and changes the uterine lining, making it harder for sperm to survive.
Developed 30 years ago, Depo-Provera was introduced in this country in 1992. It has an estimated 10 million to 30 million users worldwide, and it’s growing in popularity here, especially among teenagers, said Jennifer Frost of the Alan Guttmacher Institute, a New York-based reproductive health research organization. Frost said that in 2001, about 20% of American women who use federally funded family planning clinics used Depo-Provera.
The reason it’s popular is that it’s as effective as surgical sterilization, is reversible and doesn’t require remembering to take a pill every day, said Dr. Andrew Kaunitz of the University of Florida at Jacksonville.
It also gives users privacy: No one but your health-care provider has to know you get the shot, said Berta Portigiani of Planned Parenthood of Hudson Peconic, which serves Suffolk County in New York. It’s useful for women who can’t use a contraceptive with estrogen and for women who are breast-feeding and want to avoid getting pregnant, Portigiani said. Each shot costs between $30 and $75, according to Planned Parenthood.
It’s not a good method for someone who might want a baby soon, however: Once a woman stops taking the shots, it may take up to a year to get pregnant, said Nancy O’Keefe of Planned Parenthood of Nassau, N.Y. And it’s not without side effects (irregular bleeding, weight gain).
The bone loss and its reversal have been seen in smaller studies, but Scholes’ study is the largest with the longest follow-up so far. It included 183 women using Depo-Provera and 274 who did not. Of the 183, only 43 were first-time Depo-Provera users; the rest had been using it from a month to 11 years.
Among Depo users, bone density declined throughout the four-year study, while it increased slightly among nonusers. Bone loss at the hip was greater than at the spine. After four years of Depo use, the bone loss was like that seen in post-menopausal women and among women who are breast-feeding. The researchers said that in post-menopausal women, “this degree of bone loss would increase the risk of hip fracture by about 50%.”
But 2 1/2 years after stopping the shots, most women regained bone so that density equaled that of nonusers--although the researchers found the hip was slower to regain density. And the 18- to 21-year-old Depo-Provera users who started the study with lower bone densities still had less density 2 1/2 years later.
Kaunitz, who is conducting a similar study for Pharmacia, said that though the Scholes study “doesn’t answer every single question, the emerging picture is reassuring.” And, he said, he’d have no qualms letting someone on Depo- Provera stay on it “six months to six years to 16 years.” In a statement, the company said, based on the study, “we would ... not expect to see any long-term impact on osteoporosis from Depo-Provera use.”
Others were less reassured. “I really do think this information should weigh significantly, particularly for those under 30,” said Amy Allina of the nonprofit National Women’s Health Network.
Questions remain. Women don’t reach peak bone density until about age 30. Depo-Provera is a method popular among teenagers, so what does the study’s findings about 18- to 21-year-olds portend, especially if they use the shot for years? And what about breast-feeding women? Generally a woman regains whatever bone density she lost after she stops breast-feeding. But what happens to someone on Depo-Provera? Scholes said no one knows.
Given the recent rethinking about HRT risk, which has been studied far more than Depo-Provera, that’s disturbing.
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Ridgley Ochs writes for Newsday, a Tribune company.
