Birth control pills may block blood flow to brain

Turns out, birth control pills increase the risk of ischemic strokes which are usually caused by a blood clot that blocks or plugs a blood vessel in the brain. This keeps blood from flowing to the brain.

According to stroke specialists at the Loyola University, oral contraceptives increase the risk of ischemic stroke, but this risk is very small among women who do not have other stroke risk factors.

The findings of the study appeared in the journal MedLink Neurology.

Several mechanisms were proposed to explain why oral contraceptives increase stroke risk during the research, including raising blood pressure and making blood hypercoagulable.

"The ideal drug is one with the lowest estrogen and progestin doses that will be effective in preventing pregnancy while minimizing adverse effects," said neurologist Sarkis Morales-Vidal.

In women with other stroke risk factors, the risk is higher and, in most cases, oral contraceptive use is discouraged. These risk factors include high blood pressure, cigarette smoking and migraine headaches, especially migraines with sensory disturbances called the aura.