New York: Popping birth control pills can put you at increased risk for the most common type of stroke, especially if you smoke, have high blood pressure or have a history of migraine headaches, a new study warns.
For healthy young women without any stroke risk factors, the risk of stroke associated with oral contraceptives is small.
But in women with other stroke risk factors, "the risk seems higher and, in most cases, oral contraceptive use should be discouraged", said study co-author Marisa McGinley from Loyola University Chicago Stritch School of Medicine in the US.
Oral contraceptives increase the risk of ischemic strokes, which are caused by blood clots and account for about 85 percent of all strokes.
In the general population, oral contraceptives do not appear to increase the risk of hemorrhagic strokes, which are caused by bleeding in the brain.
There are about 4.4 ischemic strokes for every 100,000 women of childbearing age.
Birth control pills increase the risk 1.9 times, to 8.5 strokes per 100,000 women, according to the new analysis that combined the results of multiple previous studies.
This is still a small risk as the findings imply that 24,000 women would have to take birth control pills to cause one additional stroke, according to the report.
But for women who take birth control pills and also smoke, have high blood pressure or have a history of migraine headaches, the stroke risk is significantly higher.
Such women should be discouraged from using oral contraceptives, the report said.
Worldwide, more than 100 million women currently use oral contraceptives or have used them in the past.
Strokes associated with oral contraceptives were first reported in 1962, the study said.
Early versions of the pill contained doses of synthetic estrogen as high as 150 micrograms. Most birth control pills now contain as little as 20 to 35 micrograms. None contain more than 50 micrograms of synthetic estrogen, the researchers said.
The study was reported in the journal MedLink Neurology.