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    Posted on May 29, 2015

    Here’s What You Need To Know About Birth Control And Blood Clots

    Before you freak out and throw away your pills, you'll probably want to read this.

    There’s been A LOT of talk about birth control raising your risk of blood clots, especially some of the newer kinds.

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    This probably isn't news to most people — it's a well-known side effect that's been in the prescription information forever. And in the past few years, more and more studies have looked at the risk of blood clots associated with newer birth control options, like the ring, the patch, and oral contraceptives with new kinds of progestin (like Yasmin or Yaz, which contain the progestin drospirenone).

    SO here's what you need to know about your blood clot risk and how it's impacted by which birth control you use:

    Here’s what a blood clot actually is:

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    When you get a cut or scrape, blood clotting is a normal thing that happens to stop the bleeding. But when a clot forms in a vein or artery, it can be dangerous and sometimes fatal. Blood clots in veins are called venous thromboembolism (VTE), which refers to two different kinds of clotting complications and affects about 300,000 to 600,000 people in the U.S. each year. Deep vein thrombosis (DVT) is when a clot forms in a major vein (like in your legs, arms, or pelvis). Pulmonary embolism (PE) is when a clot detaches and travels to the heart or lungs, where it cuts off blood flow.

    Doctors aren't always sure what causes a clot, but there are some things that can raise your risk of developing one.

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    Some of the main risk factors for VTE are major surgery, being hospitalized for an acute illness, immobility, cancer, obesity, and trauma to your legs, ankles, hips, or pelvis, Dr. John Heit, professor of medicine in the Division of Cardiovascular Diseases at Mayo Clinic, tells BuzzFeed Life. For women, the risk of clots is also higher during pregnancy, right after giving birth, when taking hormone therapy, and when taking many types of hormonal birth control. There's also evidence that the risk of blood clots in veins is somewhat inherited, says Heit.

    Yes, being on some kinds of birth control can slightly raise your risk of blood clots. But not all of them.

    So what about this new study that says newer birth controls give you a 4x higher risk of blood clots?! OK...let's talk about that.

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    The study results — which have been making terrifying headlines this week — found that your risk of getting a blood clot is 1.8 times higher if you take birth control with a newer form of progestin than if you take birth control with an older form. They also found that the risk of a blood clot on these newer pills is up to about 4.3 times higher than if you don't take any birth control at all. Again, that sounds terrifying. The problem is, most reports aren't actually explaining what those numbers mean and giving them context — like, you know, how many people actually get blood clots...and 4.3 times higher than what?!

    BuzzFeed Life spoke with the lead study author Yana Vinogradova, research statistician at the University of Nottingham, to find out more about the study, which you can read in full here. They compared the blood clot risk associated with different types of progestin, the synthetic hormone found in some types of birth control. One of the most common progestins is levonorgestrel (found in some birth control pills, Plan B One-Step, and the hormonal IUD). But this study also looked at newer types of progestin like drospirenone (found in Yasmin or Yaz) and desogestrel (found in Desogen or Mircette).

    So here's what those numbers ~actually~ mean:

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    Based on their estimates, the rate of blood clots while not on any birth control is 4.2 per 10,000 women in a given year. (Heit and Gunter confirm that about 3 to 5 women per 10,000 will get a blood clot each year.) So that's a 0.04% chance of getting a blood clot. Very small chance, but it happens.

    For women taking a levonorgestrel-containing birth control pill (an older one), they estimated that 6 extra cases per 10,000 women would occur each year. For women taking a drospirenone-containing pill, they estimated that 13 extra cases per 10,000 women would occur each year; and for women taking a desogestrel-containing pill, they estimated 14 extra cases per 10,000 women. So we're basically looking at a difference between 0.04% chance and 0.18% chance.

    "Even though the risk is slightly increased, it's still very low," says Heit. So what causes this difference? It's thought that the estrogen in birth control is what mostly accounts for this overall increased risk, and the newer types of progestin might also directly affect the clotting mechanism or they might impact estrogen in a way that affects your clotting, says Gunter.

    Ready to have your mind blown? Your risk of getting a blood clot is 4 to 5 times higher when you’re PREGNANT, and it’s 20 TIMES HIGHER in the postpartum period.

    Jerry Lai / Creative Commons / Via Flickr: jerrylai0208

    So, yeah, even the newer birth control pills can't compete with that risk. Your risk of having a blood clot while on newer types of birth control is still lower than your risk of having a blood clot during pregnancy or the postpartum period, confirms Vinogradova. So before you throw out your pill, keep in mind that getting pregnant would up your risk even more. Basically, all those fear-mongering headlines are absolutely terrifying, but they're not telling the whole story.

    And obviously there are limitations to this (and every) study that you should keep in mind.

    So should you switch your birth control or stop taking it completely?

    One last thing! Here are the signs and symptoms of a blood clot, just so you know:

    Dirima / Getty Images / Via thinkstockphotos.com

    The symptoms of DVT in the leg often include pain, swelling, and redness usually in the calf or ankle, says Heit. It may also feel hot to the touch or feel painful behind your knee. A clot in another vein may lead to swelling and pain in other areas, but those are less common. The symptoms of PE (when a clot moves to your lungs) include shortness of breath, chest pain, rapid heartbeat, and feeling faint. Of course, these symptoms could come from a number of things, but if something feels really off, definitely see a doctor, says Heit.

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