How Birth Control Could Lower Your Stroke Risk

Stroke is one of the leading causes of death for women in the U.S., though stroke is often preventable, according to the CDC. There are many risk factors for stroke, including high blood pressure and some heart diseases, diabetes, smoking, and other habits including diet, per the National Heart and Lung Institute. Certain social factors such as race, sex, and age can also contribute to the risks of experiencing this medical emergency. Black Americans and Hispanic Americans have strokes more often than white Americans; women have a higher lifetime risk of stroke than men; and the odds of having a stroke increase with age. 

There are two main kinds of strokes, ischemic and hemorrhagic. Ischemic strokes happen when blood vessels to the brain are blocked — these are more common than hemorrhagic strokes, which occur when a blood vessel in the brain ruptures. For years, researchers have studied the link between oral contraceptive pills (OCPs) and strokes in women. In the 1970s, pills with high doses of estrogen were linked to stroke, but such formulas have since been discontinued, per a study by the American Heart Association. 

The study suggests that the risk of ischemic stroke is higher in women who use a combination OCP (estrogen and progestin) when other risk factors are present. And while OPCs can be wonderful for treating acne and menstrual cramps, for example, another study explores the negative effects hormonal birth control can have on teens. Now, though, data suggests that OCPs may actually lower the risk of stroke.

New research suggests that oral contraceptive pills could actually lower the risk of stroke in a potentially unexpected benefit of the pill. The research, conducted in China, followed a cohort of 123,000 post-menopausal women "between the ages of 40 and 79" for close to a decade, analyzing the entire length of their reproductive cycles, per U.S News. The study took into account factors that could affect the women's reproductive cycles and overall estrogen exposure — for example, their pregnancies. It also took into consideration how long they were on hormonal birth control, if at all. Researchers measured stroke incidents in the women — a total of 12,000 ischemic strokes — compared to the data. Women with longer exposure to estrogen had a lower risk of ischemic stroke by 5%, compared to those with the shortest exposure to estrogen. And higher estrogen levels overall also meant lower risk, not just longevity.  

A researcher with the Zhejiang University's School of Public Health and the study's author, Peige Song, noted that the methods did not deeply account for the effects of hormone replacement therapy or HRT, which has been shown to increase the risk of ischemic stroke, per AHA Journals. As such, "it is unclear whether estrogen replacement therapy would be as protective as a naturally long reproductive cycle," Song said (via U.S. News). Though the research did take into consideration other potential risk factors for stroke, including smoking, Song reiterated that the research had, "limited information on oral contraceptive use."