Migraines during pregnancy may be linked to stroke

Pregnant women who have one or more migraines also face a heightened risk of stroke and other vascular diseases, even during the pregnancy, a new study finds. Although strokes during a pregnancy are rare, women with a migraine listed on their medical chart face a 30-fold increase in the risk for the most common kind of stroke, researchers report online March 10 in the British Medical Journal.

Pregnancy is actually a time when women who routinely contend with migraines are often free of them. “A lot of women have a wonderful kind of honeymoon away from migraines during pregnancy,” says study coauthor Cheryl Bushnell, a neurologist at Wake Forest University in Winston-Salem, N.C.

Indeed, in a national database of more than 18 million women who were pregnant at some point from 2000 to 2003, Bushnell and her colleagues found only 33,965 women who had migraines listed on their medical charts upon discharge from the hospital — a rate well below the average.

But when the researchers checked for other ailments on the charts, they found that women with migraines were 15 times as likely to have had a stroke listed on the chart, compared with women without migraines. The stroke could have occurred before or during pregnancy. What’s more, when counting only ischemic strokes, which account for the vast majority for all people, the risk rose to 30-fold. Ischemic strokes result when a blood clot blocks a vessel in the brain.

This finding held up even when the researchers ruled out women who had preeclampsia, a pregnancy complication marked by vascular problems.

Women with a migraine during pregnancy also were eight times as likely to have had high blood pressure and showed a slightly increased risk of heart attack, diabetes and other conditions caused by blood clots — compared with pregnant women without migraines.

Meanwhile, women with migraines had no increased risk of conditions that are unrelated to vascular problems, such as pneumonia or post-partum infection.

“This is the first large-scale study suggesting that active migraine during pregnancy is a risk condition, or at least a marker of, stroke and other vascular diseases,” says neurologist Stefan Kiechl of the Innsbruck Medical University in Austria.

“Pregnancy, as a stress condition, is sometimes viewed as a window to a future vascular risk profile,” Kiechl says. But while the emergence of certain other risk factors, such as diabetes or high blood pressure, during pregnancy can signal dangers later in life, he says, “no similar data are available for migraine [because] our understanding of the mechanisms linking migraine and stroke during pregnancy is limited.” Thus, he concludes, the best doctors can do for now is closely monitor pregnant women who have migraines and be vigilant of the potentially heightened risks.

It’s not clear whether migraines in pregnancy are legitimate proxies for unseen vascular risks elsewhere in the body, Bushnell says. “But it certainly begs the question.”

“My personal bias is that if a woman has a migraine during pregnancy, she should be examined for other risk factors that may not be recognized,” she says. These could include CT or MRI scans to check for clotting, she says.