Women of all ages should pay more attention to the risk of stroke than the average man, watching their blood pressure carefully before they think about taking birth-control pills or getting pregnant, according to a new set of prevention guidelines released Thursday.

Women are also more likely to have risk factors associated with stroke, such as migraines, depression, diabetes and the abnormal heart rhythm known as atrial fibrillation.

The guidelines from the American Heart Association and American Stroke Association were the first such recommendations aimed at preventing strokes in women. Stroke is the fourth-leading cause of death for all Americans and a leading cause of disability. It’s the third-leading cause of death for women, after heart disease and cancer.

Women share many of the same risk factors as men for stroke, but they have unique risks that come with pregnancy complications and hormone use, said Cheryl Bushnell, associate professor of neurology at Wake Forest Baptist Medical Center in Winston-Salem, N.C., who led a group of experts that developed the guidelines.

Previous guidelines about cardiovascular prevention in women have included some information about stroke. “But it was buried in there,” said Bushnell, who has been studying the topic for more than a decade. “We wanted to take topics that are really women-specific and emphasize stroke and put it all in one guideline.”

The recommendations, published in the journal Stroke, emphasize the importance of controlling blood pressure, especially in young women. They are aimed at a broader age range than most recommendations.

“We’re talking about being aware of blood pressure before you ever take birth-control medication, being aware of blood pressure before you ever get pregnant,” Bushnell said.

A stroke occurs when the blood supply to the brain is blocked or when a blood vessel in the brain ruptures, causing brain tissue to die.

The signs of stroke in women are similar to those in men, including drooping of the face, sudden numbness or weakness of the arm, and difficulty with speech or trouble understanding. But symptoms in women may be more vague or subtle, Bushnell said. Women are more likely to have a change in their ability to communicate with people, she said.

An estimated 6.8 million people in the United States have had a stroke, including 3.8 million women, according to the American Heart Association. Women make up more than half of the estimated 800,000 people who have a stroke each year.

As women increasingly outlive men, their lifetime risk of stroke becomes higher. Women are also more likely to be living alone as widows when they suffer a stroke, are more likely to be institutionalized and have poorer recovery than men, research shows.

“As the baby-boomer generation ages, more people are at risk for stroke, and women in particular as they enter their 50s, 60s and 70s,” said Alexander Dromerick, a neurology professor at Georgetown University who was not among the experts working on the guidelines.

The new recommendations, he said, raise the visibility of the issue.

“Women are more adversely affected by stroke than men,” according to the guidelines. “Now more than ever, it is critical to identify women at higher risk for stroke and initiate the appropriate prevention strategies.”

In some instances, the recommendations call for common-sense precautions that doctors and consumers should already be taking. These include regular physical activity, moderate alcohol consumption, no smoking, and a diet rich in fruits, vegetables, grains, nuts and olive oil and low in saturated fat.

Other recommendations are more specific :

●Women should be screened for high blood pressure before taking birth-control pills, because the combination raises stroke risks.

●Women with a history of high blood pressure before pregnancy should be considered for low-dose aspirin or calcium supplement therapy, or both, to lower preeclampsia risk.

●Women who have preeclampsia have twice the risk of stroke and a fourfold risk of high blood pressure later in life. Therefore, preeclampsia should be recognized as a risk factor well after pregnancy.

Preeclampsia and eclampsia are blood-pressure disorders during pregnancy that cause major complications, including stroke during or after delivery, premature birth and risk for stroke well after childbearing, in some cases as long as 40 years later. Preeclampsia is characterized by high blood pressure and high protein levels in the urine, and when seizure also occurs, it is called eclampsia, according to the American Heart Association.

The guidelines also recommend that women who have migraine headaches with aura — such as blinking lights or moving dots — stop smoking to avoid higher stroke risks. Women are four times more likely to have migraines than men, research shows. Women over age 75 should also be screened for atrial fibrillation.

One recommendation that could be controversial is treating pregnant women with moderately high blood pressure (150 to 159 over 100 to 109 millimeters of mercury) with blood pressure medication. That goes against a recommendation by the American Congress of Obstetricians and Gynecologists, Bushnell said.

“We are going out on a limb,” she said. “We don’t want women to develop severe blood pressure, and that has to be weighed with risks for the mom and the baby.”

James Roberts, who chaired the American Congress of Obstetricians and Gynecologists task force on hypertension in pregnancy, said the obstetrician group suggests that in general, women with moderately high blood pressure should not receive blood pressure medication. But, he added, “there might be situations where that might be appropriate for individuals.”