The other study focused on another known risk factor for stroke -- medications containing estrogen.
"Estrogen, which is contained in hormone-replacement therapy and in certain kinds of combination birth control pills, increases the likelihood of blood clots," and thus increases stroke risk, Loder said.
Researchers analyzed data for more than 82,000 women 50 to 79 years old from the Women's Health Initiative, a study begun by the U.S. National Institutes of Health in the early 1990s. All reported having some degree of migraines, and about 45 percent were using hormone replacement.
At a follow-up visit three years later, women completed a questionnaire to determine if their migraines had gotten better or worse.
Women who experienced worsening migraines while taking hormone-replacement therapy appeared to be 30 percent more likely to have a clot-based stroke than migraine sufferers who either stopped taking or never took hormone-replacement therapy, researchers concluded.
Study lead author Dr. Haseeb Rahman, a neurology resident at Houston Methodist Hospital in Texas, said the findings suggest women on hormone replacement therapy should notify their doctor of any migraine symptoms.
"You should not simply ignore an increasingly bad migraine," said Rahman, who worked on the study with a research team from the Zeenat Qureshi Stroke Institute in Minneapolis. "You should also tell your doctor if you're getting migraines for the first time while on hormone replacement therapy."
However, Loder noted that the increased risk is "certainly higher than we would like it to be, but it's not terribly high," given that just 2,063 women experienced clot-based strokes out of more than 82,000 female migraine sufferers.
Migraine sufferers or women taking estrogen should address more important risk factors, Loder said, by quitting smoking, controlling theirblood pressure, treating their diabetes or lowering their cholesterol.
Data and conclusions presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.
SOURCES: Elizabeth Loder, M.D., M.P.H., chief, Division of Headache and Pain, Brigham and Women's Hospital, Boston; Souvik Sen, M.D., M.P.H., neurologist, University of South Carolina School of Medicine; Feb. 17, 2016, abstract, American Stroke Association annual meeting, Los Angeles