A contraceptive that has become popular in the past decade may impair the arteries' ability to contract and expand, possibly increasing the risk for heart disease, according to a new study.

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Depo-Provera, or depot medroxyprogesterone acetate, had been considered a good drug for women who may have some cardiac risk factors such as smoking or high blood pressure or a family history of heart disease, according to researchers from the Imperial College School of Medicine in London.

But their study found that women with cardiovascular disease risk factors "would be wise to review that decision with their physician," said Dudley Pennell, a cardiology professor.

According to the study, published in Monday's rapid access issue of Circulation: Journal of the American Heart Association, the drug affects the arteries' ability to "respond to different stimuli and particularly affects the ability of the artery to dilate," Pennell said. Problems with arterial response can reduce blood flow, which can damage the heart.

The researchers measured vascular function in 12 women who used Depo-Provera for at least a year and compared the results to those of nine women who didn't use the injectable contraceptive.

They found that blood vessel dilation was significantly reduced in women who used Depo-Provera.

However, the drug is an effective contraceptive that can be safely used by women who are otherwise healthy and who have no cardiovascular risk factors, Pennell said.

Depo-Provera was approved by the Food and Drug Administration in 1992 after a decade of controversy. It is considered 99.7 percent effective.

One hormone shot that will prevent pregnancy for 12 weeks. Researchers said the shot is a very effective birth control method for women who have limited access to health care or for women who have trouble complying with oral birth control or barrier contraceptives.