In absolute terms, the number of women likely to have stroke from taking the pill rises from about three women to six per 10,000 a year, say the Dutch researchers.
Ischemic stroke is caused by insufficient blood flow to the brain, most commonly due to a blood clot that blocks circulation.
Oral contraceptives (OCs) are a mixture of synthetic female hormones. First-generation birth control pills, introduced in the 1960s, contained very high doses of estrogens and the progestogens lynestrenol or norethisterone. These pills were associated with an increased risk of blood clots, known as thrombotic events. Blood clots can travel to the heart, causing a heart attack, or to the brain, causing a stroke.
In the early 1970s, second-generation birth control pills were developed with the intent to reduce thrombotic events. They contain low estrogen (less than 50 micrograms) and the progestogen levonorgestrel.
A decade later, third-generation OCs were developed to try to decrease side effects associated with the progestogens in the second-generation preparations such as weight gain, acne and adverse changes in cholesterol levels. Third-generation formulations also contained less estrogen than first generation but combined them with different progestogens: desogestrel or gestodene.
Previous studies of second-generation OCs found an increased stroke risk particularly among smokers and women with high blood pressure. There is limited data on third-generation pills.
In the current study, researchers assessed the risk of ischemic strok
Contact: Carole Bullock or Bridgette McNeill
American Heart Association