The changes that happen in the body during pregnancy can cause blood clotting. But the risk of deep vein thrombosis (DVT) is low.
Deep vein thrombosis (DVT) is a blood clot that develops in a deep vein in the:
- upper extremities, like the arms (less frequently)
DVT is not common during pregnancy, but pregnant people are
Blood-clotting protein levels increase during pregnancy, while anticlotting protein levels decrease. This helps reduce the amount of blood lost during delivery.
The enlarging uterus during pregnancy may also increase the risk because it puts the veins of the lower body under additional pressure to return blood to the heart.
Read on to learn more about DVT and pregnancy.
The most obvious symptom of DVT is swelling and heavy pain or extreme tenderness in one of your legs. Approximately
- pain in the leg when standing or moving around
- pain in the leg that worsens when you bend your foot up toward your knee
- warm skin in the affected area
- visible veins that appear enlarged
- discoloration or red skin at the back of the leg, typically below the knee
- bluish toes
- slight to severe swelling
The chances of having asymptomatic DVT before or after pregnancy
You may experience muscle cramps during pregnancy. They typically affect the calf during the second and third trimesters, particularly at night. Muscle cramps during pregnancy are not a medical emergency.
They can be prevented or relieved with:
- stretching and movement
- magnesium supplements
- comfortable, supportive footwear
Muscle cramps do not cause leg swelling. Unlike muscle cramps, stretching and moving around will not improve pain from DVT.
A pulmonary embolism (PE) is a blood clot that travels to the lungs. DVT
- sudden shortness of breath
- chest pain or tightness in the chest
- a cough that produces blood-streaked sputum (mucus)
- rapid heartbeat
PE is a medical emergency
If you or someone you know has PE symptoms such as shortness of breath or chest pain, contact 911 or your local emergency services immediately.
See a doctor as soon as possible if you suspect DVT. Diagnosed DVT is not a medical emergency and is unlikely to harm you or your baby unless there are serious complications. It’s best to get checked early to begin DVT treatment.
It’s not always easy to diagnose DVT in pregnancy from symptoms alone. A doctor may order multiple tests to confirm the diagnosis, including:
- D-dimer test: This blood test identifies pieces of a blood clot that have broken off into your bloodstream. D-dimer levels above a certain threshold
may indicatea higher risk of PE, but doctors typically conduct further testing because levels normally fluctuate during pregnancy.
- Doppler ultrasound: This scan determines how fast blood flows through a blood vessel. A Doppler ultrasound helps a healthcare team establish whether blood flow is slowed or blocked, a possible sign that indicates a blood clot.
- Venogram: If a D-dimer test and ultrasound cannot confirm a DVT diagnosis, a doctor may use a venogram or magnetic resonance imaging (MRI). A venogram involves injecting a liquid called a contrast dye into a vein in your foot. The dye moves up the leg. The dye shows on an X-ray, which pinpoints a gap in the blood vessel where the clot stops the blood flow.
According to a 2019 review of over 40 studies, a venogram is the “gold standard” for a DVT diagnosis.
A doctor can form a treatment plan if you develop DVT during pregnancy. They may refer you to a specialist, such as a hematologist (blood specialist) and a maternal medicine or obstetric medicine specialist.
To treat DVT, a doctor may recommend once or twice daily injections of the blood-thinning agent low-molecular-weight heparin. This treatment may help to:
- stop the clot from getting bigger
- help the clot dissolve in the body
- reduce the risk of further clots
You’ll likely have regular checkups and blood tests to ensure the clot dissolves and no further clots appear.
A doctor may recommend at-home practices for DVT in addition to medication. These may include daily walks, keeping the affected leg elevated when sitting, and following your prescribed anticoagulant medication schedule.
DVT during pregnancy typically does not affect the baby unless there are serious complications. Doctors and researchers consider heparin safe to use during pregnancy because it doesn’t cross the placenta, so there is no risk to your baby.
Depending on your anticoagulation regimen, you must stop taking injections as soon as you begin labor, or at least 12 to 24 hours before inducing labor or a planned cesarean delivery.
If you want to nurse your baby, you will have to stop the injections after birth. For those with a mechanical heart valve, a doctor may prescribe warfarin (Jantoven) to ensure the baby’s blood doesn’t thin.
This medication carries significant risks for you and your baby, particularly before birth. Fetuses exposed to warfarin
Discuss whether the benefits outweigh the risks with a doctor. Together, you may decide not to breastfeed or to stop taking anticoagulants while nursing your baby.
Untreated, DVT can have lasting effects on the body.
- Long-term DVT can lead to permanent swelling of the veins and fluid retention.
- In rare cases, a clot can dislodge and move to the lungs, resulting in a PE.
- Another rare complication from DVT is venous gangrene of the toes or fingers.
- Irreparable damage to the veins from DVT may result in chronic post-thrombotic syndrome. This is a collection of symptoms associated with leg pain and ulcers.
Finally, taking anticoagulants raises the risk of side effects like bleeding. Report any unusual bleeding, such as nose bleeds, bloody stool/urine, or bruising, to a doctor if you take these medications.
Factors that can increase your risk for DVT during pregnancy include:
- having a previous history of clots or DVT
- having a family history of DVT
- being over 35
- having a BMI of 30 or higher
- carrying twins or multiple babies
- having fertility treatment
- having had a previous, recent cesarean delivery
- sitting still or being bedridden for long periods
- having preeclampsia
- having certain chronic conditions such as high blood pressure (hypertension) and inflammatory bowel disease (IBD)
- having severe varicose veins
Race and DVT risk
Research indicates that DVT and PE occur
There isn’t a way to definitively prevent DVT in pregnancy. But taking certain steps can help to reduce your risk:
- Stay active with pregnancy-safe exercises.
- Wear compression socks during air travel and walk around at least once every hour.
- Move your legs when sitting down, for example, by raising and lowering your heels and your toes and flexing your ankle.
- Wear support hose.
- Quit smoking, if you smoke.
- See a doctor immediately if you notice any pain, tenderness, redness, or swelling in your legs.
Pregnant people at high risk for DVT
While DVT isn’t common in pregnancy, it’s a serious condition that can be fatal if the clot dislodges and moves into the lungs.
Be aware of the symptoms and risk factors if you are pregnant or at risk for DVT. Let a healthcare professional know right away if you suspect DVT.
Early treatment and ongoing management can help keep you and your baby safe.
Before labor and even after you have your baby, it’s important to regularly check your legs for signs of DVT. Diagnosed DVT related to pregnancy is treatable.
Since pregnancy alters the body’s natural anticlotting process, doctors may recommend that people with pre-existing blood clotting disorders and a higher BMI take extra precautions.