Left uterine displacement increases venous return by relieving pressure on which vessel?

• A. Aorta
• B. Pulmonary artery
• C. Inferior vena cava
• D. Superior vena cava

Answer: (C)

When a pregnant person lies on their back, the enlarged uterus can press on the inferior vena cava, hindering blood from the lower body returning to the heart. Shifting to the left relieves that pressure, allowing venous blood to flow more freely through the IVC into the right atrium. This increases preload, which boosts cardiac output and helps prevent or treat the low blood pressure that can occur in late pregnancy (supine hypotensive syndrome). The other vessels—the aorta, the superior vena cava, and the pulmonary artery—aren’t compressed by the uterus in this position, so the primary mechanism for the rise in venous return is relief of IVC compression.