- Abstract Objectives: To investigate parturients at risk to develop venous thrombo-embolic events (VTE) in the puerperium or later in life, during a follow-up of more than a decade , and compare risk factors for VTE during the puerperium with VTE later in life. Methods: A nested case-control study was conducted to profile parturients at risk for VTE and a secondary analysis to compare risk factors for VTE during or after puerperium. We used a cohort of 95,257 women that gave birth between the years 1988-1998. Results: Independent risk factors to develop VTE were peripartum hysterectomy, stillbirth, cesarean delivery (CD), obesity,pregnancy related hypertension, grandmultiparity and advanced maternal age. Women undergoing CD and these receiving blood transfusion were more likely to develop early vs. late VTE (OR=2.0, 95% Cl=1.15-3.5, and OR=11.0, 95% Cl=2.25-55.5; respectively.(Patients that encountered VTE during the puerperium had more pulmonary emboli and less deep vein thrombosis , compared with the late VTE group (p< 0.001). Conclusions: Maternal age, grandmultiparity, pregnancy related hypertension, CD, obesity, stillbirth and peripartum hysterectomy are independent risk factors for the development of VTE. CD and blood transfusion were predictive of early vs. late VTE.