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.
A pregnant woman who is diagnosed with deep vein
thrombosis or pulmonary embolism will work with her doctor to decide which anticoagulant medicine to take during pregnancy. She may take heparin, because it has not been shown to affect
After delivery, the woman might take another anticoagulant, such as warfarin, for a few weeks or a few months.
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.