Postpartum Heparin Against Venous Thromboembolism: a Pilot Randomized Controlled Trial

Inclusion Criteria: adult women within 48h of delivery, with: * ≥2 of the following risk factors Age ≥35 years Pre-pregnancy BMI 30.0-34.9kg/m2 Current smoking Elective cesarean section Postpartum hemorrhage Antenatal immobility * and/or ≥1 of the following 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 (\<37th week of gestation) Peripartum systemic infection (defined as fever with use of antibiotics) Intra-uterine growth restriction (birth weight \<5th percentile) Exclusion Criteria: * any indication for therapeutic anticoagulation * a high-risk of postpartum venous thromboembolism (personal history, high-risk thrombophilia) * an increased bleeding risk * a contra-indication to the use of heparin