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

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

The new guidelines from the American Heart Association were the first such recommendations to prevent strokes in women. Stroke is the fourth-leading cause of death for all Americans but 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 also 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 even 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 face drooping, 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 consciousness or their ability to communicate with people, she said.

An estimated 6.8 million people in the United States are living after having had a stroke, including 3.8 million women, according to statistics from the American Heart Association. More than half of the estimated 800,000 people who have a stroke each year are women.

As women increasingly outlive men, their lifetime risk of stroke becomes higher. Women are also more likely to be living alone and widowed after suffering a stroke, and are more likely to be institutionalized, 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 Alex Dromerick, a neurology professor at Georgetown University.

“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 doing. In others, the recommendations are more specific.

Some highlights of the new guidelines:

BIRTH CONTROL PILLS: Women should be checked for high blood pressure before starting on oral contraceptives because the combination raises stroke risks. The risk is small but rises steeply in women ages 45 to 49. More than 10 million American women use birth control pills.

PREGNANCY: Strokes are uncommon during pregnancy but the risk is still higher, especially during the last three months and soon after delivery. The big worry is preeclampsia, dangerously high blood pressure that can cause a seizure and other problems. “It doubles the risk of stroke later in life and it quadruples the risk of high blood pressure” after pregnancy, Bushnell said.

Women with a history of high blood pressure before pregnancy should be considered for low-dose aspirin (around 81 milligrams) after the first three months of pregnancy, and calcium supplements anytime, to lower the risk of preeclampsia, the guidelines say.

Pregnant women with very high blood pressure (160 over 110 and above) should be treated with medications, and treatment may be considered for those with moderately high blood pressure (150 to 159 over 100 to 109). Certain blood pressure medicines are not safe during pregnancy, the guidelines note.

ASPIRIN: It’s usually recommended for anyone who has already had a stroke unless the stroke was caused by bleeding rather than a clot, or if bleeding risk is a concern, Bushnell said. Aspirin also is often recommended for people with diabetes to lower the risk of stroke and other problems.

A low-dose aspirin every other day “can be useful” to lower stroke risk in women 65 and older unless its benefit is outweighed by the potential for bleeding or other risks, the guidelines say.

MIGRAINES: Women are four times more likely to have migraines than men, and they often coincide with hormone swings. Migraines alone don’t raise the risk of stroke, but ones with aura do. Using oral contraceptives and smoking raise this risk even more, so the guidelines urge stopping smoking.

IRREGULAR HEARTBEAT: Women over age 75 should be checked for atrial fibrillation. Doctors do this by taking a pulse or listening to the heartbeat.

MENOPAUSE: Hormone therapy should not be used to try to prevent strokes.

The new guidelines put women’s issues “on the table” so more doctors talk about them, said Dr. Shazam Hussain, stroke chief at the Cleveland Clinic. “Gender does make a difference. The medical community has neglected it for some time.”