BACKGROUND: Venous thromboembolism (VTE) remains the most common cause of maternal mortality in the developed world. VTE is up to 10 times more common in pregnant women than non-pregnant women of comparable age. More than a third of pregnancy related VTE occur during the brief postpartum period (6 weeks). When compared with vaginal delivery, cesarean delivery further increases the risk of pregnancy associated VTE by three-fold. Pregnancy associated VTE is unique in that isolated iliac vein thrombosis is more likely and long term morbidity (post-phlebitic syndrome) is common.