Following institutional ethical committee approval, 20 morbidly obese (BMI>40) and 20 non-obese (BMI < 30) parturients undergoing elective low segment cesarean section (LSCS) delivery under spinal subarachnoid block will be recruited into the study. A written informed consent will be obtained from all parturients prior to inclusion. All patients will receive an information sheet at the preoperative assessment visit to inform them about this study. Patients with a history of past or current thromboembolism will be excluded from the study as well as those with liver disease and those already on anticoagulant/anti-platelet therapy for repeated miscarriage or other indications. History of thromboembolism is defined as an arterial or deep venous thrombosis, catheter thrombosis, or pulmonary embolism diagnosed by ultrasound or spiral computed tomography (CT). Preoperative baseline full blood count and clotting profile will be done. Parturients with abnormal platelet count or coagulation results and those who will need conversion to general anesthesia will be excluded.