This is the most important risk factor you can change. Smoking causes inflammation and damages the smooth muscle that lines the arteries. This makes them less flexible. It also raises your blood pressure, causing more damage to the artery lining. Smoking also increases the risk that your blood may clot, block an artery, and lead to a heart attack or stroke. This risk is further increased if you take birth control pills (oral contraceptives). Smoking also damages your lungs, which can affect the delivery of oxygen to the body. Research shows that smoking makes women up to 6 times more likely to have a heart attack. It's also important to stay away from secondhand smoke. This is smoke from other people's tobacco products. If you smoke, it's never too late to protect your heart. Ask your health care provider about ways to help you quit. You may want to try nicotine replacement products, other medicines, or counseling.