This is a prospective study using duplex ultrasound techniques to characterize venous flow in obese and non-obese pregnant patients. Women will be consented to participate and then separated into a study group of obese women (BMI >/= 30) and a control group of non-obese women (BMI <30). These women will be admitted to Labor and Delivery for management of pregnancy. The Doppler US will then be performed by trained staff on the lower extremity. The flow data described above will be measured and compared between the two groups. Additional measurements will be collected during hospitalization.