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

The goal of this clinical trial is to evaluate the risk-benefit of a short-term treatment with a low-dose low-molecular-weight heparin (LMWH), in the postpartum period (after delivery). The main questions it aims to answer are: * compared to no treatment, does short-term postpartum LMWH modify the risk of venous thromboembolism within 90 days of delivery? * compared to no treatment, does short-term postpartum LMWH modify the risks of bleeding and wound complications? Participants will take low-dose LMWH for 7-10 days or no treatment, and will be followed for 90 days post-delivery.