What hormones are in birth control pills?
Birth control pills (also called oral contraceptives or hormonal contraceptives, BCPs for short) are the most commonly used form of birth control in the US. Most common BCPs contain a combination of two hormones, estrogen and progestin (although some pills contain only progestin).
Most women take low-dose birth control pills, which have 50 micrograms or less of estrogen. Modern birth control pills contain 20 to 50 micrograms of estrogen—more than 50 micrograms is considered “high-dose.” Older birth control pills contained up to 5 times as much estrogen and 10 times as much progestin as modern pills. Because studies found that these older pills caused serious complications including stroke, heart attack, and blood clots in the lungs ( pulmonary embolism), the amounts of hormones were reduced.
Do birth control pills affect stroke risk?
Using birth control pills raises your risk of stroke a small but significant amount. In healthy young women (non-smokers under age 35 who do not have high blood pressure), the overall risk is low.
There is controversy over whether the modern low-dose pill (<50 micrograms of estrogen) increases the risk of stroke, but if it does, the increase is very small. In women younger than 35 who do not smoke or have high blood pressure, the risk of stroke is 10 per 100,000 women, and this only increases to about 13 per 100,000 in women taking birth control pills.1 Women who use high-dose pills (>50 micrograms of estrogen) are more likely to have a stroke because the high hormone doses increase the chances of developing blood clots.2 A Dutch study looking at the risks associated with older versus newer generation birth control pills found that the risk of stroke in women using the newer (third-generation) oral contraceptives (containing the hormones desogestrel or gestodene) was not different from that in women using the older (second-generation) oral contraceptives (containing levonorgestrel).3
