Long-term use of birth control pills can increase the risk of heart disease.

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Here's some bad news: Women on long-term (more than five years) use of oral contraceptives are at increased risk for heart disease. The American College of Obstetricians and Gynecologists stands by its October 1994 Technical Bulletin, warning of the heart risks posed by oral contraceptives (the Birth Control Pill).

That bulletin indicated studies in the '60s and '70s suggesting that women using high-dose oral contraceptives are at increased risk for thromboembolism (a blood clot in a vein), myocardial infarction (death of heart muscle), and stroke (in laymen's terms, a brain attack).

But these complications are occurring less frequently, according to Bruce Stadel, MD, at NICHD as a result of lower hormone content in oral contraceptives, better screening of women who might be at high risk, and, perhaps most importantly, the recent drop in pill use among women over 35.

What Are the Odds of a Pill-related Heart Attack?

Pill-related heart attacks are very rare. They occur in an estimated one in 14,000 users between the ages of 30 and 39. Between the ages of 40 and 44, the risk rises to about one case in 1,500 women on the pill. Strokes occur five times more frequently among women taking oral contraceptives.

But they are a rare event, too, affecting about one in every 2,700 women on the pill. Although blood clots occur more often than heart attacks or strokes, they are still uncommon, affecting about one in 500 previously healthy women on the pill. Hormone changes in pregnancy cause clots far more frequently than pills do.

Who are the High-risk Women?

The vast majority of heart attacks and strokes among contraceptive pill users occur in women who smoke, women over 35, and women with other health conditions, such as high blood pressure, that ordinarily contribute to cardiovascular risk. Women with a combination of two or more of these factors carry the greatest risk of all.

Some research shows that the length of pill use can affect the chances of having a cardiovascular complication. A recent study found that women age 40 to 49 who had taken the pill for five or more years had twice the average heart attack risk — even years after they stopped taking the pill. Heavy smoking adds far more to the chances of having a heart attack, however.