Varicose veins
Varicose veins can indicate a heightened risk for deep vein thrombosis. (For Spectrum Health Beat)

Did you know that your blood volume can increase by up to 50 percent during pregnancy? This provides more circulation for the growing uterus and baby and it also prepares you for the loss of blood at delivery.

There are other significant changes your blood can undergo when you’re pregnant.

One rare occurrence involves deep vein thrombosis. It happens in about 1 of every 1000 pregnancies, but all women should still learn to recognize the symptoms.

Deep vein thrombosis is a clot, typically in the lower extremities.

In nearly 90 percent of the cases involving pregnant women who develop deep vein thrombosis, the clots will form primarily in the left leg. The primary concern, however, is the clot will break off and go to the lungs, where it’s then a pulmonary embolism.

Some of the symptoms of deep vein thrombosis:

How can I prevent deep vein thrombosis?

  • If your obstetrician approves, get plenty of exercise.
  • Wear support hose.
  • If you’re sitting for long periods of time, move your legs and feet around.
  • Try to walk around and stretch every few hours.
  • Occurs in one or both legs.
  • Slight to severe swelling.
  • Painful feeling in the affected leg.
  • Tenderness and/or warmth.
  • Pain in the calf when flexing your foot.
  • Redness in the sore area.

Some of the risk factors for deep vein thrombosis:

  • Smoking.
  • Body mass index of 30 or higher.
  • Undergoing fertility or hormone treatments, or taking medications that thicken the blood.
  • Pregnant with twins or more.
  • Previously had a clot (thrombosis).
  • Age 35 or older.
  • Thrombophilia, a condition in which your blood clots easily.
  • Family member had thrombosis.

Deep vein thrombosis is more common when you’re inactive after a surgery, such as cesarean section, or when you’re severely dehydrated. Severe varicose veins can also indicate a greater risk, as can chronic diseases such as preeclampsia, diabetes or other vascular conditions.

If you have a history of deep vein thrombosis or if a risk factor applies to you, your doctor may have you wear a special kind of stocking called compression stockings, as well as taking medication to help thin your blood.

A pulmonary embolism, meanwhile, has a few other symptoms to watch for:

  • Chest pain or tightness.
  • Difficulty breathing.
  • Rapid breathing rate.

If you notice these symptoms, you need to contact your obstetrician immediately or go to the hospital.

Diagnosis of the blood clot can be done by an ultrasound or an MRI. The medication used, an anticoagulant, may change during and after the pregnancy. It’s normal to be on the anticoagulant, or blood-thinning medicine, for several months after delivery.

The medication thins the blood so the body can break down the clot; it also keeps other clots from forming. Once this medication is started, it is not to be stopped without a provider’s orders.