Blood Clots in Pregnancy Most Likely Occur on Left Side


Pregnancy increases the risk of deep vein thrombosis (blood clots) and pulmonary embolism, a blood clot that travels to the lungs and blocks the flow of oxygen. Researchers from the Women’s College Hospital reviewed several studies that indicate that the blood clots are more likely to occur in the left side than the right, particularly the left leg, in pregnant women.

The review article, published in the Canadian Medical Association Journal, evaluated 1098 papers and found six that had the appropriate inclusion criteria for the study. In all, 88% of the 124 women had deep vein thrombosis (DVT) in the left leg. Dr. Wee-Shian Chan said that the review was conducted “in order to (possibly) limit diagnostic procedures, such as x-rays, because of the effects on the fetus.”

In a related commentary, Dr. Ristaa Kajaa, Professor of Medicine at Turku University in Finland, said that the increased prevalence of isolated proximal vein DVT is clinically important because of the high risk of pulmonary embolism.


According to the National Alliance for Thrombosis and Thrombophilia (NATT), one to two women in every 1,000 will get a venous thrombosis during pregnancy or just after delivery. IN a pregnant woman, the clot is normally found within a leg or the pelvis, while those not pregnant typically have blood clots that begin in the calves. Thrombosis can affect anyone, but being pregnant makes the blood more likely to clot. There is also a reduction in the flow of blood throughout the body, another factor for the increased risk.

Women at increased risk for developing DVT’s during pregnancy include moms over 35 years of age, excess body weight, immobility prior to labor (ie: bedrest), or a medical condition such as infection or paraplegia.

The usual symptoms of DVT include pain, tenderness, and swelling of the leg and possible discoloration (a pale blue or reddish-purple color). The diagnosis of DVT is usually confirmed by an ultrasound scan of the leg. Treatment includes heparin, an anti-coagulant medication. Warfarin (Coumadin), another popular anti-coagulant medication, cannot be used in pregnancy as it has been associated with causing birth defects.

Chan WS, et al "Anatomic distribution of deep vein thrombosis in pregnancy" CMAJ 2010; DOI: 10.1503/cmaj.091692.

Kaaja R "Is deep vein thrombosis different during pregnancy?" CMAJ 2010; DOI: 10.1503/cmaj.100279.



im 11 weeks pregnant, at 7 weeks i deveolped blood clot in both lungs, im on clexane and have to take it daiy till the en on my pregnancy + 6 weeks after i give birth