Teens who stopped using injectable contraceptive regained density
By Amanda Gardner
HealthDay Reporter
MONDAY, Feb. 7 (HealthDay News) -- The bone loss experienced by teenagers who use Depo-Provera for birth control appears to be reversible.
New research found that when the teens stopped using the popular injectable contraceptive, their bone density went back to normal levels for their age group.
The finding appears to run counter to a Food and Drug Administration black-box warning issued in November 2004 stating that bone loss from using Depo-Provera "may not be completely reversible" even after stopping the drug. The warning urged women not to use Depo-Provera on a long-term basis unless all other methods were inadequate.
The new bone density research is "a very important thing to document, and it's very reassuring," said Delia Scholes, lead author of the study, which appears in the February issue of Archives of Pediatric and Adolescent Medicine. The study was funded by the National Institute of Child Health and Human Development.
"It does seem to be reassuring," added Dr. Loren Wissner Greene, a clinical associate professor of medicine at New York University School of Medicine in New York City. Women also lose bone density during pregnancy and breast-feeding, then regain it.
"There is in the premenopausal woman an incredible ability to recover bone density," Greene added.
About 10 percent of American females aged 15 to 19 who use birth control use Depo-Provera, compared with 3 percent of women in the United States overall. The method is convenient (an injection once every three months), effective and relatively inexpensive.
One drawback, however, has been a loss of bone mineral density documented in several studies.
Even before the FDA warning last year, however, other research had started to indicate that the pattern of bone loss did reverse itself. A study conducted by Scholes found that women aged 18 to 39 regained their bone density after stopping the injections.
Scholes was still concerned about the adolescent population, however.
"Teens are really in the process of building their peak bone density. They're undergoing some of their most rapid gain," said Scholes, who is an investigator at the Center for Health Studies at the Group Health Cooperative in Seattle. "We were thinking they might be particularly affected by Depo, which shuts down a lot of estrogen production."
Scholes and her colleagues measured hip, spine and whole-body bone densities in 170 women, aged 14 to 18. Eighty received Depo-Provera, and 90 did not. Additional measurements were collected at six-month intervals over two to three years. During that time, 61 of the teenagers using Depo-Provera stopped, allowing the researchers to track what happened to their bone density.
Those who used Depo-Provera had an average bone density loss at the hip of 1.81 percent each year vs. .19 percent per year among nonusers. Among Depo-Provera users, loss of bone at the spine was 0.97 (similar to women who are breast-feeding or going through menopause), while nonusers had an increase of 1.32 percent. Women who had just started using the drug lost bone density at a quicker rate than those who had been on it longer.
Women who stopped using Depo-Provera experienced an average bone gain of 1.34 percent at the hip versus a loss of 0.19 percent for women who never took the drug. Spine density increased 2.86 percent for women who stopped using, compared to an increase of 1.32 percent for nonusers.
Teens regained their bone density faster than older women using Depo-Provera.
Although the results for Depo-Provera are reassuring, the drug does have other drawbacks. Recent research showed that women who use it have 3.5 times the risk of contracting the sexually transmitted diseases chlamydia and gonorrhea. It was unclear why this was the case.
As Scholes pointed out, however, all contraceptives have pluses and minuses, and Depo-Provera is no exception.
"It is very effective, and has a fair number of advantages. It also has disadvantages," she said. "It's reassuring when you're making a complex decision about which contraceptive is best for you that bone density is one consideration, but perhaps a less salient one than it was, given our results. Now women can turn their attention to other pros and cons."
Scholes also said she hoped the black-box warning could incorporate language acknowledging these results.
Regardless, women should not forget diet, Greene stressed. "This doesn't mean that people should not be concerned about getting enough calcium and vitamin D," she said.
SOURCES: Delia Scholes, Ph.D., investigator, Center for Health Studies, Group Health Cooperative, Seattle; Loren Wissner Greene, M.D., clinical associate professor, medicine, New York University School of Medicine, New York City; February 2005 Archives of Pediatric and Adolescent Medicine
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