What raises the risk of blood clots during pregnancy?
The three main risk factors (things that increase risk) for
deep vein thrombosis and
pulmonary embolism are abnormal clotting, reduced
blood flow, and damage to the veins. These risks are all higher during
pregnancy, most likely because of:
Changes in hormone levels and blood composition
that influence clotting.
Reduced blood flow in the legs due to the
weight of the fetus pressing upon veins.
For pregnant women who are diagnosed with deep vein
thrombosis or pulmonary embolism, treatments may include:
anticoagulant medicine. Heparin is used because it has not been shown to affect
Warfarin, another type of anticoagulant. This
medicine can be used after delivery. Warfarin may cause miscarriage or birth
defects if used during pregnancy. There
is also an increased risk of bleeding in the fetus and the mother, particularly
during the third trimester.
If a woman has deep vein thrombosis during or after
pregnancy, anticoagulant medicine is usually continued for a few weeks to a few months after giving birth.
American College of Obstetricians and Gynecologists (2011). Thromboembolism in pregnancy. ACOG Practice Bulletin No. 123. Obstetrics and Gynecology, 118(3): 718–729.
Tapson VF, Becker RC (2007). Venous thromboembolism.
In EJ Topol, ed., Textbook of Cardiovascular Medicine,
3rd ed., pp. 1569–1584. Philadelphia: Lippincott Williams and
How this information was developed to help you make better health decisions.