Dec. 13 (Bloomberg) -- People who suffer from migraines are twice as likely to have a stroke than non-sufferers because of a reduced blood flow to their brains during a severe headache, according to a report in this week's British Medical Journal.

The risk of stroke for migraine sufferers was 2.16 times above those who don't have the periodic headaches, said lead researcher Mayhar Etminan from the Royal Victoria Hospital in Montreal. Women also taking a contraceptive pill were eight times more likely to suffer a stroke than those not on the pill.

Migraine is the most common form of headache in young adults and stroke trails only heart disease and cancer as killers in the western world. It's the first time scientists have shown that migraines may be a risk factor for stroke.

``Data from observational studies suggest that migraine may be a risk factor in developing stroke,'' the researchers said in the study. ``The increased risk of stroke is probably down to the reduced blood flow to the brain which usually occurs in a migraine.''

The scientists analyzed 14 studies that investigated a link between stroke and migraine. They also found that those who have a so-called aura with their migraine have a slightly higher risk than those migraine-sufferers who don't have these visual disturbances.

Every 45 seconds, someone in the U.S. has a stroke, making it the country's No. 3 killer and a leading cause of severe, long- term disability, according to the American Stroke Association.

Migraine is the most common neurological condition in the developed world, affecting 10 percent of the U.K. population, according to the Migraine Action Association's Web site.

To contact the reporter on this story: Chantal Britt in Stockholm at cbritt@bloomberg.net.

Last Updated: December 12, 2004 19:24 EST