Blood Clots During Pregnancy

Pregnant women run a big risk of developing harmful blood clots. Although blood clotting is a normal function of the body since it prevents uncontrolled bleeding, blood clot formation in wrong places can be harmful and sometimes fatal.

Overview of Blood Clots

Pregnant women have a high risk of developing blood clots, whether or not they have blood clotting abnormalities before pregnancy - a condition called thrombophilia. These blood clots usually develop in the deep veins, especially in the legs and pelvic area. The formation of a blood clot or thrombus in the deep veins is called deep-vein thrombosis. If the thrombus is dislodged and travels in the blood stream to the lungs, an event known as pulmonary embolism occurs. This is a life-threatening condition. Harmful blood clots can also form in the placenta and can cut off the blood flow to your baby.

Your risk of forming blood clots during pregnancy is greater when you have the following conditions:

  • You are obese
  • You have been in prolonged bed rest or inactivity
  • You have a history of Caesarian deliveries
  • You are genetically predisposed to form blood clots
  • You have had a previous venous thrombosis
  • You have been diagnosed with thrombophilia
  • You are over 35 years old
  • You are pregnant with more than one baby
  • You have increased blood pressure (severe pre-eclampsia)
  • You are a smoker

What are the Symptoms of Blood Clots during Pregnancy?

When a blood clot forms inside a deep vein in the leg, you may feel discomfort or severe pain, redness and swelling in the leg. Known as deep vein thrombosis, this condition may become life threatening when the blood clot is dislodged from the site of formation and travels in the blood. The blood clot can become stuck in smaller blood vessels in the lung, a condition known as pulmonary embolism. This will manifest as difficulty in breathing which can result in death. If the thrombus or blood clot goes to the heart one will experience a heart attack, while a thrombus that reaches the brain may result in a stroke.

To determine if you have blood clots in the lower leg veins or anywhere in the body, an ultrasound or other imaging techniques must be done.

What are the Risks of Blood Clots during Pregnancy?

Compared to a non-pregnant woman, a pregnant woman is at greater risk for developing blood clots, whether or not she has thrombophilia. This is because normal changes during pregnancy occur in blood clotting mechanisms that serve to limit the blood loss during the process of delivering the baby. However, studies have found that pregnant women who have thrombophilia disease have a greater risk of pulmonary embolism, which is the leading cause of death among pregnant women in the US.

Aside from pulmonary embolism, pregnant women who have blood clotting abnormalities are at risk for repeated miscarriages, stillbirths (death of the fetus which occurs during the later stages of pregnancy), and placental abruption. Placental abruption occurs when the placenta is peeled away from the uterus before delivery, causing heavy bleeding which is dangerous to both mother and her baby.

Some women who develop an autoimmune condition that results in acquired thrombophilia are also at risk for pre-eclampsia, which is high blood pressure associated with pregnancy. This can also result in poor growth of the fetus and premature delivery of the baby. These events may be due to blood clot formation in the placenta.

How are Blood Clots Treated?

Blood clots are treated using blood thinning agents called heparin which is injected in the abdomen. This can be self administered after a health care provider teaches you how to do it. Heparin reduces clot formation and prevents them from bigger by dissolving them. This also prevents them from getting lodged into smaller blood vessels in the lungs, heart or brain. Heparin treatments last throughout pregnancy and six weeks beyond. Blood clot formation can also be prevented by wearing compression stocking. Oral medications like warfarin (another blood-thinner) should not be taken during pregnancy because these may cause harm to the baby.