Birth Control Shot May Cause Bone Loss Depo-Provera Linked to Steady Declines in Density

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Birth Control Shot May Cause Bone Loss

Depo-Provera Linked to Steady Declines in Density

By Salynn Boyles

Reviewed By Brunilda Nazario, MD

on Friday, May 14, 2004

WebMD Medical News

May 14, 2004 -- New research confirms that the injectable

contraceptive Depo-Provera promotes steady bone loss, but it is not

yet clear if using the birth control method increases a woman's

osteoporosis risk later in life.

Women in the study who used Depo-Provera for two years had losses in

bone mineral density of roughly 6%, compared with a loss of 2.6%

among women on birth control pills. Those using no hormonal

contraceptives averaged a 2% increase in bone density during the same

period.

The rate of bone loss among Depo-Provera users remained consistent

throughout the two-year study, but researchers say the findings

should not prompt women to abandon the highly reliable birth control

method. Earlier studies suggest that the bone loss associated with

Depo-Provera use is largely reversible once injections are stopped.

" Right now we only have part of the picture, and my concern is that

women will stop using this highly effective method of birth control

before we know the whole story, " lead researcher Abbey B. Berenson,

MD, tells WebMD.

Declines Averaged 3% Per Year

Approved for use in the U.S. in 1992, Depo-Provera is given by

injection every three months and is a popular form of birth control

among young and low-income women.

In their study, Berenson and colleagues from the University of Texas

Medical Branch, Galveston, followed 191 women between the ages of 18

and 33 using either Depo-Provera, oral contraceptives, or non-

hormonal birth control. The findings are reported in the May issue of

the journal Obstetrics and Gynecology.

Depo-Provera users had declines in bone mineral density averaging 3%

each year. A similar rate of decline was reported last year in a

trial involving 148 teens using Depo-Provera, but that study's lead

researcher tells WebMD that injectable contraception is still the

best choice for many sexually active teenagers.

" This issue definitely needs more study, and it suggests that we need

to be aggressive in recommending calcium replacement and exercise to

minimize bone loss, " says adolescent gynecologist Lara-Torre,

MD.

Reversible Losses?

Epidemiologist Delia Scholes, PhD, is one of the few researchers to

follow women after they stop using Depo-Provera. In a study first

reported two years ago, involving 182 adult users of the injectable

contraceptive and 258 nonusers, Scholes and colleagues found that

users recovered bone steadily over time after stopping injections.

Bone mineral density values among Depo-Provera users were similar to

those of non-users within two and a half years of discontinuing the

birth control.

Scholes tells WebMD that her most recent research suggests the same

is true for teens. Bone mineral density losses averaged 4.5% among 14-

to 18-year-olds using the injectable birth control method for two

years, but users regained bone rapidly once they stopped using Depo-

Provera.

" Our research is encouraging in that it suggests gains and recovery

in bone following discontinuation, " she says. " We are seeing the same

pattern in teens that we have seen in adults. "