Today is the American Heart Association’s 11th Annual National Wear Red Day. The day, which is celebrated on the first Friday in February each year, is dedicated to raising awareness about heart disease, specifically as the condition relates to women. Since the National Wear Red Day’s first celebration in 2003, the organization has made tremendous strides in the fight against heart-related diseases in women.

"Heart disease has been called the Silent Killer because it often has no noticeable symptoms. It's more deadly than all forms of cancer combined. And it’s not just 'an old man’s disease,'" explains the American Heart Association's Go Red for Women.

In furthering the Wear Red Day’s efforts, here are 4 facts that may surprise you about women and the fight against heart disease:

1. Heart disease is the number one killer of women in the United States. According to the American Heart Association, heart disease was killing nearly 500,000 women each year when Wear Red Day began in 2003. Since then, 21 percent fewer women are dying from heart-related conditions, but it remains the number one killer of women.

2. Women are at a greater risk for stroke than men. Guidelines published Thursday in Stroke, a journal of the American Heart Association, particularly focus on stroke prevention in women. The guidelines are geared toward risk factors that are more prevalent in women than men. Exercise, birth control, and pregnancy may all impact women’s risk of stroke. The hope is that by compiling data and raising awareness, women and their health care providers can take steps toward prevention. "The take-home here is really about starting prevention earlier," said Dr. Cheryl Bushnell, an associate professor at Wake Forest Baptist Medical Center, according to NPR.

3. Celebrities in entertainment and fashion have joined in raising women’s awareness of heart disease. One of the most attended events at New York Fashion Week each year is the Red Dress Collection. At that event, stars from television, music, film, and fashion strut their stuff in red dresses to raise awareness about the cause. TV attorney Star Jones, talk show host Daphne Oz, and actress Taryn Manning are among the big names that participated in this year’s show.

4. Birth control and pregnancy can both impact your heart health. Blood pressure levels during pregnancy can put you at high risk of developing long-term heart problems, especially if you have a pre-existing heart condition. The American Heart Association suggests speaking to a doctor before getting pregnant and asking questions about blood pressure medication. The American Heart Association also recommends talking to your physician, gynecologist, and cardiologist before starting birth control.

For more information on heart disease in women, visit GoRedForWomen.org.