What Is DVT During Pregnancy?

Doctor with a pregnant person in medical masks during an examinations.

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Swelling during pregnancy is a relatively common occurrence, from larger-than-normal ankles to feeling like your face somehow looks puffier. But while certain types of swelling might be expected, there are others that should never be ignored, as they can be signs of a larger and more serious problem. One such condition is known as deep vein thrombosis (DVT), which can lead to even more worrisome complications.

So how do you know if your swelling is normal or something to worry about? We turned to some experts to learn more about DVT, what the symptoms look like, what can be done to prevent it, and when to contact your healthcare provider.

What is DVT During Pregnancy?

Deep vein thrombosis (DVT) is a condition that occurs when you develop a blood clot deep within a vein, usually one located in the leg. However, the clots can occur in other places, like the thigh, pelvis, or arm.

DVT is a condition that you might not have thought about before getting pregnant. But it's an issue that pregnant people do need to consider, as they are five times more likely to develop deep vein thrombosis than people who aren't expecting. 

Moreover, DVT can lead to other complications, including post-thrombotic syndrome (PTS), which is damage to the veins that may cause leg pain, discoloration, and/or swelling. The most serious complication of DVT is pulmonary embolism. A pulmonary embolism is a blood clot that breaks off and travels to the lungs. A small clot can damage your lungs, but a larger one can block the flow of blood, which can be fatal.

Causes of DVT During Pregnancy

“Hormone shifts are responsible for changing the protein factors that affect clotting. That, in and of itself, can cause clotting to be more prevalent,” explains Eileen de Grandis, MD, a vascular surgeon with Baptist Health South Florida. 

Additionally, as a pregnancy progresses, the fetus grows larger and can put pressure on the vena cava, which is one of the largest blood vessels in the body. If you lie flat on your back while sleeping or resting, you can end up compressing that vessel further. This can make your blood pressure drop, in a condition known as supine hypotension syndrome, which can slow down circulation. “When we slow down blood flow, that’s when we start getting clots,” says Dr. de Grandis. 

Risk Factors for DVT During Pregnancy

“Anyone can get DVT during pregnancy, although some factors increase the risk,” says Monte Swarup, MD, an OB/GYN and founder of HPD Rx

If you’re at least 35 years of age, you’re at elevated risk for developing DVT during pregnancy. Carrying multiples raises your risk, because of the added weight, and the chances are also higher if you undergo a C-section. Other factors that increase your risk for DVT include:

  • Having a blood clot in the past
  • A family history of blood clots
  • A history of smoking
  • Severe varicose veins
  • A blood clotting disorder or other medical conditions that include a risk for clotting
  • Body-mass index of 30 or greater
  • Being immobilized
  • Undergone fertility treatment
  • Recent serious injury or infection

Symptoms of DVT During Pregnancy

DVT doesn’t always have noticeable symptoms. Other times, the signs are just vague enough that a pregnant person might wonder if they’re imagining something. “It can often be dismissed as the kind of leg swelling that’s common in pregnancy,” says Dr. de Grandis. 

But unlike the normal swollen ankles of pregnancy, DVT is more likely to occur in just one leg, rather than both. In fact, one of the most common symptoms is swelling and pain or tenderness in one leg, often the lower portion of your leg. Your skin may also develop some redness or warmth at the affected area.

It's important to know that if you start feeling short of breath or notice pain in your chest, you may be experiencing a pulmonary embolism. If you experience either of these symptoms, be sure to contact your healthcare provider and call for emergency help right away.

How is DVT Diagnosed During Pregnancy?

Dr. de Grandis encourages pregnant people to check in with their healthcare provider if they have an inkling that something just isn’t right. Your instinct could lead to a diagnosis. “Keep in mind these symptoms that are different from your normal pregnancy swelling,” adds Dr. de Grandis. “Don’t ignore something that feels off.”

Your doctor may examine your leg and then follow up with some testing. For example, a test commonly used to detect DVT is one that looks for a protein fragment in your blood called D-dimer, which is created when a blood clot dissolves. It’s a simple test that just requires a blood draw from one of your veins. 

Your physician might also order an ultrasound of your leg. A Doppler ultrasound can show how fast blood is flowing through a blood vessel, so your doctor can gauge if the vessel might be partially blocked by a clot. In some cases, an MRI may be helpful, too. 

Treatment for DVT During Pregnancy

Even though you’re at greater risk for developing DVT during pregnancy, most pregnant people don’t need to take anticoagulants during pregnancy. But if you do develop DVT, the question of balancing the potential risk of treatment with the benefits becomes important. 

If you have DVT, you’ll likely need to take a blood-thinning medication to reduce or eliminate an existing clot and prevent future ones from occurring. Your doctor may recommend daily injections of the anticoagulant enoxaparin sodium, which is a type of low molecular-weight heparin. Often sold under the brand name Lovenox, this drug blocks the activity of certain proteins, which helps prevent your blood from clotting. It’s considered safe for expecting people to use, and it’s used both to treat and prevent DVT during pregnancy. 

However, this treatment can carry a risk for bleeding, among other side effects, so your healthcare provider may want to discuss those with you. Dr. de Grandis also cautions that long-term use of this medication can take a toll on your bone mineral density. If you develop DVT and need to take the medication for a long period of time, you may need to take vitamin D or calcium supplements and undergo BMD monitoring. 

Coping with DVT During Pregnancy

Of course, taking any medication that your healthcare provider prescribes for you is paramount. But your physician may also talk to you about some coping mechanisms. That might include educating yourself about your condition, as well as taking steps to reduce the likelihood of future clots. It might even include some self-care measures that help you stay calm and focused. 

“It’s very important to consult with your OB/GYN if you are pregnant to understand your options,” says Dr. Swarup, adding that you should also talk to your doctor about the four-to-six-week period after you give birth because you’re still at elevated risk for developing DVT during that period. 

Preventing DVT During Pregnancy

Treatment is available, but prevention should be your first goal. Prevention of DVT can take a couple of different forms. 

Wear Compression Stockings

Compression stockings or socks should be your go-to accessory when it comes to preventing blood clots. “Consider wearing them,” says Dr. de Grandis. “It’s a nice way of being proactive about your own health.” 

The compression helps your circulation, which reduces the likelihood of a clot forming in your legs. “In essence, it squeezes the blood back up to where it’s supposed to go, instead of just having it sit there,” says Dr. de Grandis.

You don’t necessarily have to buy the old tan (read: ugly) compression stockings of your grandmother’s era, either. Dr. de Grandis notes that many running and athletic stores now sell compression socks in a variety of colors and patterns, so you can have a little fun with it. 

Move Your Legs

If you’re traveling—and especially if you’re going to be sitting for four or more hours—make a concerted effort to move your legs frequently. Stand up and walk around, or do seated leg exercises and stretches. This can aid in circulation.

You might also ask your healthcare provider about other exercises that are safe to do during pregnancy. 

A Word From Verywell

You are more likely to develop blood clots during pregnancy than when you’re not pregnant. But even if you are at elevated risk, you can do your part by keeping a sharp eye out for developing symptoms and by doing what you can to prevent DVT. If you do notice that one of your legs is swelling—or anything that looks or feels different, even if you can't quite put your finger on it—call your healthcare provider right away and ask for guidance.

10 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Jennifer Larson
Jennifer Larson is a seasoned journalist who regularly writes about hard-hitting issues like Covid-19 and the nation's ongoing mental health crisis, as well as healthy lifestyle issues like nutrition and exercise. She has more than 20 years' of professional experience and hopes to log many more.