You may be aware of some pregnancy complications like gestational diabetes and preeclampsia. But there’s one more pregnancy complication you should know about, since it can result in serious consequences: blood clots.
Deep vein thrombosis (DVT) is a type of blood clot that tends to be more common in pregnant women and can lead to a serious condition known as pulmonary embolism (PE). Fortunately, DVT and PE are treatable and even preventable among women who are at risk; most moms with blood clotting conditions have perfectly healthy pregnancies and deliveries.
Here’s what you need to know about DVT to protect your health and your baby’s during and after pregnancy.
What is deep vein thrombosis (DVT)?
Deep vein thrombosis, or DVT, is the development of a blood clot in a deep vein.[1] During pregnancy, up to 90% of DVTs occur in the left leg. Early treatment can keep a clot from breaking off and traveling through the circulatory system to the lungs (called a pulmonary embolism, or PE), which can be life-threatening.
How common is deep vein thrombosis (DVT)?
Venous thromboembolism (VTE), which includes both deep vein thrombosis and pulmonary embolism, occurs in about 2 in every 1,000 pregnancies.
While those numbers make it a relatively uncommon complication, VTE actually crops up about four to five times more frequently in expecting women than in other women of the same age — and 20 times more frequently in the six weeks after birth. By eight weeks postpartum, your risk should drop back to normal.
"The risk is highest in the first six weeks postpartum and declines to rates that [align with] that of the general population by about 13 to 18 weeks," says Andrei Rebarber, M.D., a board-certified OB/GYN with a speciality in maternal fetal medicine, and a member of the What to Expect Medical Review Board.
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What are the signs of deep vein thrombosis (DVT) during pregnancy and postpartum?
The most common symptoms of deep vein thrombosis during pregnancy and postpartum usually occur in just one leg and include:
- A heavy or painful feeling in the leg (a lot of people say that it feels like a really bad pulled muscle that doesn’t go away)
- Tenderness, warmth and/or redness in the calf or thigh
- Slight to severe swelling
If the blood clot has moved to the lungs and you have PE, you may experience:
- Chest pain that gets worse when you take a deep breath or cough
- Unexplained shortness of breath
- Coughing up blood
- Rapid or irregular heartbeat
Concerned about DVT during pregnancy or postpartum? Track your symptoms and get more information on the What to Expect app.
Other than the higher chance of developing left-sided DVT and iliac vein thrombosis, DVT during pregnancy is identical to that in nonpregnant women.
"I’m always worried that I’m going to get a DVT," says What to Expect Community mom cmreis98. "The nature of my job requires me to stand all day, so there’s nothing I can do besides continue wearing compression socks and rest when I get home."
Why is deep vein thrombosis (DVT) more common in pregnancy and postpartum?
DVT may be more common during pregnancy because nature, wisely wanting to limit bleeding at childbirth, tends to increase the blood’s clotting ability around birth — occasionally too much.[2]
Experts do know that during pregnancy, the level of blood-clotting proteins increases, while anti-clotting protein levels get lower.
Other factors that can contribute to DVT during pregnancy may include an enlarged uterus, which increases pressure on the veins that return the blood to the heart from the lower body, as well as lack of movement due to bed rest.
Who is most at risk for deep vein thrombosis (DVT)?
DVT is more common if you:
- Have a family or personal history of VTE
- Having thrombophilia (an inherited or acquired blood clotting disorder)
- Are overweight or obese
- Smoke
- Are on strict bed rest
- Have preeclampsia or certain chronic illnesses including hypertension, diabetes, inflammatory bowel disease, or other vascular diseases
- Delivered by cesarean section
- Have a postpartum hemorrhage or need a blood transfusion
Can you prevent deep vein thrombosis (DVT)?
Be sure to let your doctor know if you have a clotting disorder or if blood clots run in your family. You should also be aware of the signs of a blood clot, since early treatment can reduce the risks of complications like PE.
You can help prevent clots and DVT by keeping your blood flowing in the following ways:
- Getting plenty of pregnancy-safe exercise (as long as you have the okay from your practitioner).
- Walking and stretching if you've been sitting for more than two to three hours (for example, if you’re on a flight).
- Moving your legs while you’re sitting (raise and lower your heels and then your toes).
- Taking extra precautions when you travel, including drinking lots of water, getting up frequently to walk, or stretching your legs from a seated position.
- If you're at high risk, your doctor may recommend regularly wearing a support hose (although they are not proven to prevent blood clots). Your practitioner may also prescribe a preventative dose of the blood thinner heparin (or low molecular weight heparin), sometimes during the whole pregnancy or just for several weeks after birth. (Both types of medication do not cross the placenta, so they're safe to take during pregnancy.)
Does DVT during pregnancy have any effects on your baby?
DVT is a type of venous thromboembolism (VTE), a term for a blood clot in any vein. VTE has been linked to preeclampsia. Many people with preeclampsia have healthy pregnancies and deliver healthy, thriving babies. Left untreated, however, preeclampsia may lead to pregnancy complications.
About 15 to 20% of all cases of DVT are linked to antiphospholipid syndrome (APS), an autoimmune disorder that increases the risk of developing blood clots. (A tendency to have blood clots, in turn, is known as thrombophilia.)
APS has been linked to increased risk of recurrent miscarriage, blood clots in the placenta, placental insufficiency (when the placenta is less efficient at getting food and oxygen to the baby), intrauterine growth restriction (IUGR), and heart attack and stroke in the mother.
Let your doctor know if you’ve had blood clots in the past or recurrent miscarriages; your practitioner may want to run blood tests to check for APS.
When to see your doctor
If you or someone in your close family, such as a parent or sibling, has been diagnosed with DVT, let your practitioner know. Your doctor may run a blood test to see if you have thrombophilia, which increases your risk of blood clots. If you have thrombophilia, your doctor may want to start you on blood thinners just to be on the safe side.
In addition, if you notice any of the above symptoms (especially during pregnancy or within the first eight weeks after birth), call your practitioner immediately. Your doctor may give you a test (including a blood test, ultrasound, or other imaging test) to diagnose a DVT or PE.
If it turns out that you do have a clot, your practitioner will likely treat you with the blood-thinning medication heparin to decrease the blood's clotting ability and prevent further clotting (though your doctor will make other arrangements when labor begins so the heparin doesn't make you bleed excessively during childbirth). Your doctor will also monitor your blood-clotting ability along the way.
- DVT is rare but more likely during and shortly after pregnancy, so it's important to know the signs and talk to your doctor if you're at risk. Even though DVT affects only a small percentage of pregnant women, the risk is significantly higher during pregnancy and especially in the first six weeks postpartum.
- Most cases of DVT are treatable and even preventable with the right care and early attention to symptoms. Knowing the signs — like leg pain, swelling, and redness — can lead to early treatment, helping to prevent serious complications like pulmonary embolism.
- You can take simple steps to lower your risk, such as staying active, wearing compression socks, and sharing your health history with your doctor. Personalized care, including blood thinners or lifestyle adjustments, can help ensure a safe pregnancy and recovery for you and your baby.
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