context: When a blood clot forms in one of your deep veins, it's called deep vein thrombosis ( DVT). This can cause pain and swelling. If the clot breaks free, it can move through your bloodstream to other parts of your body. In rare cases, it can even cut off blood flow to your lungs. DVT is tough to detect. That's why it's a good idea to know what puts you at risk so you can avoid getting it. Here are some things that increase your chances of DVT: You've already had a blood clot. About 30% of people who've had DVT will have it again. You have a family history of it. If a parent or sibling had DVT, you're more at risk. If both your parents have been diagnosed, your chances may be even higher. You're over age 40. The odds that you'll get DVT increase with your age. You're on bed rest or sit for long periods of time. The deep veins in the center of your legs depend on your muscles to force blood back to your lungs and heart. If your muscles don't move for a while, blood starts to pool in your lower legs. This makes it more likely for a clot to form. You're pregnant or just gave birth. When you're expecting a baby, your levels of the female hormone estrogen rise. This causes your blood to clot more easily. If you take birth control pills or hormone replacement therapy, your chances of DVT also go up. That's because many of these drugs contain estrogen. Your blood doesn't clot like it should. Some people are born with a blood clotting disorder. This can cause your blood to be thicker than normal when it moves through your body. You need to lose weight. The higher your body mass index ( BMI), the greater your risk for DVT. BMI measures how much fat you have compared to your height and weight. You have other health issues. People with heart disease, lung disease, and inflammatory bowel disease are more likely to get DVT. So are people who have cancer or are going through cancer treatment. Your vein has been injured. If you badly hurt your muscle or fractured a bone, the inner lining of a nearby vein could have been damaged. This makes a clot more likely. Major surgery to your stomach, pelvis, hip, or leg also makes you more prone to DVT. You can't change many of the things that could lead to DVT. But try these 6 tips to keep your blood moving through your body the way it should: Don't sit for too long. Get up and stretch or walk around at least every 2 hours. It can also help to move your legs while you're seated. Raise and lower your heels while keeping your toes on the floor, or lift your toes while keeping your heels on the ground. Get moving as soon as you can after surgery. This will lower your chances of a blood clot forming. Even doing simple leg lifts in bed will help keep blood flowing through your veins. Talk to your doctor. If you think you're at risk for DVT, your doctor might advise you to take blood thinners. These are drugs that help prevent clots. He may also suggest that you wear compression stockings. These stockings fit tightly around your ankle but become looser as they go up your leg. They make it harder for blood to pool in your legs. Plan your travel. If you know you'll be sitting on a train, plane, or in a vehicle for a while, stand up often and stretch your legs. Make sure to wear loose clothing. Drink lots of water and avoid alcohol. If your body doesn't have enough fluid, your blood vessels narrow and clots are more likely to form. Stay active. Regular exercise lowers your chances of getting a blood clot. Even walking can help. Take care of your health. That may mean losing weight or giving up smoking. If you have heart disease, diabetes, or another chronic illness, follow your doctor's orders to manage these health issues.