Women's Health Birth Control and Blood Clots: The Medication Matters By Heart and Vascular Institute, March 10, 2015 You may have heard that birth control pills raise the risk of developing a blood clot. The overall risk of developing a clot for most women on birth control pills is low, but some factors can increase your risk, including which type of medication you take. In addition to medications, you may be at an additional risk for deep vein thrombosis (DVT) if you’re a smoker or have a family history of blood clots. Learn more to gain a better picture of whether you’re at risk for deep vein thrombosis. Hormone Levels Make a Difference Pills that contain drospirenone, a man-made version of progesterone and common in newer pills, may raise the risk for blood clots. The increase is estimated at about 1.5 fold over other birth control pills. To put the risk into perspective, the Centers for Disease Control and Prevention (CDC) estimates that between three and nine women per year — out of 10,000 women on birth control — will develop a blood clot. That’s between 0.03 percent and 0.09 percent. For women not pregnant and not on birth control, between one and five will develop a blood clot. Estrogen seems to be the cause of this increased risk, because it changes your body’s clotting ability. Pills, patches, or rings with higher levels of estrogen appear to have a higher risk of blood clots over lower-dose options. RELATED: Beware of Blood Clots: What You Should Know Understand Your Personal Risk for Blood Clots On its own, the risk of developing a blood clot is probably not enough reason to stop using hormonal birth control methods. However, combined with other factors such as smoking, being overweight, or having a family history of blood clots, your risk is higher. If you’ve had a blood clot before or regularly get blood clots, you may want to stay away from hormonal forms of birth control. Most doctors recommend that women over age 35 who smoke should not take birth control pills because of the spike in risk for blood clots. Always talk to your doctor about your risk for developing a blood clot before starting or switching birth control medications. To learn more about how birth control and other medications may increase your risk of developing deep vein thrombosis (DVT), visit the UPMC Heart and Vascular Institute online or call 1-855-UPMC-HVI (876-2484) to make an appointment to speak with an expert.