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Using ultrasound scans to look at the femoral artery in the leg and the carotid artery in the neck, the researchers found a surprising incidence of atherosclerosis among otherwise healthy women who had taken the pill.
Atherosclerosis is the hardening and narrowing of the arteries. It is caused by the slow buildup of plaque on the inside of walls of the arteries. Atherosclerosis, or furring of the arteries, typically occurs with age. Complications include heart attack or stroke, which occur when unstable pieces of plaque break off and block a blood vessel leading to the heart or brain.
"These are small plaques," not nearly large enough to block an artery, Rietzschel said. However, any plaque is thought to raise the risk of heart disease.
The study showed that there was a 20 to 30 percent increased prevalence of plaque for every 10 years of oral contraceptive use.
About 16 million American women currently take birth control pills and hundreds of millions have used them since they were first sold in 1960. Most combine synthetic estrogen and progestin in various doses.
The lead study investigator Dr. Ernst Rietzschel pointed out: "What we knew was that there was a risk of forming clots from taking pill, but once you stopped you had no residual risk," then he added. "Our data show that if you take the pill for a long time you have accumulation of damage that gives you risk even after stopping."
However, he cautioned that the findings do not mean that women should suddenly abandon this form of birth control.
"The implications are not that women should stop taking the pill. They should look at reducing other risk factors for cardiovascular disease," said Ernst Rietzschel, who is cardiologist at the University of Ghent in Belgium.
He stated: "They should watch their blood pressure and cholesterol levels, exercise and eat right. If they can limit their exposure (to oral contraceptives), that's good too."
To his surprise he indicated: "It's incredible that a drug which has been taken by 80 percent of women ... is almost bereft (deficient) of any long-term outcome data, safety data."
"We are coming to a stage where we might see the clinical consequences," he said. "We are the foot of a wave, but we cannot gauge the height of the wave that is coming."
Dr. Suzanne Steinbaum who was not involved in the study in response to this research said: "It is a staggering statistic that there is a 20 to 30 percent increased risk in plaque formation in women who had used the pill for a decade, which becomes evident at a relatively young age."
"Certainly, like hormone replacement therapy recommendations are qualified in certain patients who are at risk for breast cancer, the recommendation for using the pill might need to be changed in those patients who are at risk for heart disease, and perhaps they should use another form of birth control," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at the Lenox Hill Hospital's Heart and Vascular Institute in New York, N.Y.
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