By Amy Norton
That possibility has been a concern, mainly based on studies of younger women with migraines. Those studies linked hormonal birth control pills to a small risk of stroke, particularly among women whose migraines feature "aura" symptoms -- most often, visual disturbances such as seeing zigzag lines or bright flashes.
Less has been known about any risks of hormone replacement therapy, said Dr. Jelena Pavlovic, the lead researcher on the new study.
"It appears safe for women with migraines to use hormone therapy, in terms of their cardiovascular risk," said Pavlovic, an assistant professor of neurology at Albert Einstein College of Medicine in New York City.
That said, she added, the general advice for women is to talk to their doctor about the benefits and risks of hormone therapy -- and to start "low and slow."
That's the advice of groups such as the American College of Obstetricians and Gynecologists. They recommend that women only use hormone therapy at the lowest dose and for the shortest length of time needed to ease menopause symptoms such as hot flashes and night sweats.
Doctors have been cautious about menopausal hormone therapy ever since 2002, when results were reported from a large U.S. government study called the Women's Health Initiative (WHI).
It found that women who were given menopausal hormone therapy -- with estrogen and progestin, or estrogen alone -- faced health risks. They included heightened odds of breast cancer, blood clots and stroke.
Since then, studies have suggested the situation is more nuanced. Hormone therapy seems safer, for example, for relatively younger women at the beginning of menopause. (Women in the WHI were, on average, in their early 60s.)
It's remained unclear, Pavlovic said, whether women with migraines can safely go on hormone therapy.
It's estimated that migraines affect 1 in every 4 women, she said.
For the new study, Pavlovic and her colleagues combed through data from the WHI.
They found that of more than 85,000 participants with no history of heart disease or stroke, 8,800 women had suffered from migraines. During the study period, just over 1,100 women overall developed heart disease, a stroke or blood clots in the legs or lungs.
The researchers found no evidence that women with migraines were more likely than others to suffer those complications. And migraine sufferers who were given hormone therapy faced no greater risks than those given a placebo.
Dr. Huma Sheikh is an assistant professor of neurology at Mount Sinai's Icahn School of Medicine in New York City.
She said the new findings are "encouraging."
At one time, Sheikh said, many doctors treating women with migraines would have considered hormones to be "off the table."
"But now they're becoming more open to it," she said. That's partly because hormones are prescribed at lower doses today versus years ago, Sheikh noted.
The current study has limitations, Pavlovic acknowledged. For one, it looked at women's risk of cardiovascular problems overall, and not their risk of stroke specifically.
The researchers were also unable to look separately at women who had migraines with aura.
Sheikh said further studies are needed to validate these findings -- and to sort out whether certain women with migraines might face risks from hormone therapy.
For now, she suggested first trying nonhormonal ways to manage menopausal symptoms.
If women do consider hormone therapy, Sheikh added, their overall health has to be taken into account -- including whether they have risk factors for heart disease and stroke, such as high blood pressure and diabetes.
The findings were scheduled for presentation this week at the annual meeting of the North American Menopause Society, in Philadelphia. Studies presented at meetings are usually considered preliminary until published in a peer-reviewed journal.