Did you know that pregnant and postpartum women are at increased risk for blood clots? This is true for several reasons.
As the uterus gets bigger, it compresses the large blood vessels that return blood to the heart, so blood moves more slowly in the legs.
In pregnancy, the blood gets “sludgier,” or thicker. Clotting factors change, and clots form more easily. This may be nature’s way of reducing the amount of blood lost during delivery.
In late pregnancy, we move around less, and less movement means a higher risk for blood clots. Ask any truck driver or frequent flyer.
It takes a little longer for small blood clots to dissolve in pregnancy, so they sometimes become bigger clots.
How to know if your risk is high
So how do you know if your risk is high enough to worry about? The answer, again, depends on several things:
- Your family history
- Your personal medical history
- Your mode of delivery (vaginal delivery or cesarean delivery)
- The presence of certain risk factors (obesity, hypertension, twins, heart disease, autoimmune conditions)
- Inherited abnormality in your clotting
Your OB provider will probably ask you several questions about your history. For example, have you ever had a blood clot in your leg or lung? Has any close relative had a blood clot?
If the answer to either of these questions is yes, you may be tested for blood clotting abnormalities. We look for inherited thrombophilias (blood clotting abnormalities that increase the risk of clotting) and antiphospholipid syndrome (when your body makes antibodies that make your blood more likely to clot).
Symptoms and diagnosing
More than half of blood clots in pregnancy happen in the third trimester or in the first few weeks after delivery. The most common site for clots is in the legs or the lungs. If you have swelling and pain in your leg, contact your provider right away. Remember that swelling is very common in pregnancy and right after delivery, and most of the time it’s no big deal.
What’s more concerning is sudden swelling and pain in one leg, or groin pain, or sudden onset of shortness of breath. If you experience this, call your provider or go to the hospital.
The best way to diagnose a blood clot in your leg veins is with ultrasound. If we suspect a clot in your lung, we order a chest X-ray followed by a test called a ventilation-perfusion scan or a CT of your chest. These are low-radiation procedures and are considered low-risk for moms and fetuses.
Treatment for blood clots
Once a blood clot is diagnosed, it needs to be treated. The recommended treatment in pregnancy is low-molecular-weight (LMW) heparin. This is given as an injection twice daily.
Heparin does not cross the placenta, so no worries about your baby receiving any of this medication. The injections are continued until just prior to delivery. You will need to be anticoagulated for a total of about 3-6 months usually, so medication is resumed after delivery.
But there are additional options after delivery. You may not need to take injections. After delivery, oral medications like warfarin can be considered. Warfarin is considered safe for breastfeeding moms, and who wouldn’t prefer a pill to an injection?
If you have experienced a blood clot with your pregnancy, you will probably need to receive anticoagulants with future pregnancies, but at a lower dose.
The best way to avoid clots is to stay active. Walk every day during pregnancy, and move your feet, legs, and ankles around if you are sitting or lying around during pregnancy. Get up and walk as soon as you can after delivery, especially a cesarean delivery.
All women who are having a cesarean delivery will wear squeezy stockings called pneumatic compression devices; these usually stay in place from the time you are admitted for delivery until you are up and walking around, which helps reduce the likeliness of clotting.