Short-term Low-dose Low-molecular-weight Heparin to Prevent Postpartum Thrombosis

Inclusion Criteria: postpartum women after delivery AND ≥1 major risk factor / ≥2 minor risk factors: * Major risk factors: Emergency cesarean section ; Pre-pregnancy BMI ≥35kg/m2 ; Known low-risk thrombophilia (heterozygous factor V Leiden; heterozygous G20210 prothrombin mutation) ; Pre-eclampsia ; Pre-term delivery ; Peripartum systemic infection ; Intra-uterine growth restriction ; Pregnancy loss * Minor risk factors: Age ≥35 years ; Pre-pregnancy BMI 30.0-34.9kg/m2 ; Current smoking ; Elective cesarean section ; Postpartum hemorrhage ; Antenatal immobility Exclusion Criteria: * ≥2 doses of postpartum LMWH * Any indication for therapeutic anticoagulation * A high-risk of postpartum VTE * An increased bleeding risk * A contra-indication to heparin