The blood clots that cause deep vein thrombosis (DVT) and pulmonary embolism can occur suddenly, and they can be fatal. Knowing the risk factors that make deep vein thrombosis more likely in women will allow you to make choices to help prevent this condition. 

Need to Know: 14 Risk Factors for DVT

Creating a picture of your DVT risk means considering many different aspects of your life. Your risk factors include those you can't change, such as your age and a family history of clots. Some risks you can change, such as smoking or being sedentary.

The 14 major risk factors for deep vein thrombosis in women, according to Andra James, MD, a specialist in obstetrics and gynecology at the University of Virginia School of Medicine in Charlottesville, and The Surgeon General's Call to Action to Prevent Deep Vein Thrombosis and Pulmonary Embolism are:

1. Age. Women’s DVT risk increases with age over 60, regardless of other factors.

2. Ethnicity. Caucasians and African American are at higher risk.

3. Family history. About one third of young people who have DVT have an inherited blood clot disorder.

4. Personal history. A previous blood clot increases your risk of future clots.

5. Pregnancy. Your clot risk goes up during pregnancy and for six weeks after delivery.

6. Injury or surgery. Such events can trigger a clotting response, which is part of the healing process, but can also cause blood clots. Always let doctors know about your risk factors if you are preparing for a surgery so they can take steps to protect you.

7. Hormone-based medication. Women who are taking hormone therapy that includes estrogen, such as birth control pills, medications for menopause symptoms, and certain cancer treatments, all have increased DVT risk.

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8. Being a smoker. Chemicals found in tobacco smoke can damage your blood cells.

9. Lack of physical activity, immobility. Sitting or lying down for extended periods, like long plane flights or car trips, increases blood clot risk.

10. Obesity. People with a body mass index (BMI) of 30 or higher are two to three times more likely to have a blood clot.

11. Active cancer. Cancer and cancer treatments double or triple clot risk.

12. Other health problems. Certain acute infections, kidney disease, diabetes, long bone fractures, and neurological diseases that affect movement in your legs all can add to your risk of DVT.

13. Hospitalization. People who are hospitalized may have 10 times the risk of DVT compared to those who are not. 

14. Living in a nursing home. Residents have more than twice the risk of DVT. 

“The risk factors interact and begin to multiply with one another,” said Dr. James.

Symptoms and Screening for DVT

Symptoms of blood clots, which most commonly form in the legs, include unexplained pain, swelling, and discoloration in the affected leg. You might also have pain when you walk. Sometimes, blood clots occur without symptoms.

If a blood clot moves to the lungs, becoming a pulmonary embolism, symptoms may include shortness of breath, pain when you breathe, and bloody coughs. 

DVT is usually diagnosed by ultrasound. Your doctor might also recommend other imaging tests to find out if you have a clot blocking your blood, such as a study of the veins, called venography, or a CT scan or MRI. 

Pulmonary embolism is diagnosed with a lung scan. Your doctor will also consider your family and personal history, other risk factors for clotting, and the results of blood tests. 

Controlling Risk After DVT

Because having had one DVT or pulmonary embolism puts you at risk for another, you might need to take medications, such as warfarin or another oral anticoagulant, to reduce the risk of future clots. Always tell your other medical specialists, including your dentist, once you've had a blood clot, and if you are taking medication to prevent future blood clots.

Carefully consider future medical treatments. For example, women with a history of DVT who are not taking anticoagulant medication to prevent future blood clots should avoid hormone therapies. Talk to your doctor about alternative options for preventing pregnancy, managing menopause symptoms, or treating cancer.

“There are non-hormonal alternatives to manage the symptoms of menopause, and it depends on what sign or symptom of menopause needs to be treated,” said Dr. James. 

You can reduce your risk of future blood clots, even if you have a strong personal history or other risk factors. Make sure you take any medications or precautions your doctor has recommended. And live a lifestyle that lowers your blood clot risk. Things you can do include to “stop smoking, exercise, and lose weight,” advised James, if you have these risks.