What is Inferior Vena Cava syndrome?

The inferior vena cava runs along the right side of the spine and carries blood back to the heart. In the latter stages of the pregnancy, the growing uterus may compress the vein when the pregnant woman lays on her back. If the compression is high, this may cause the return of blood to the heart to be reduced to a point where it causes a drop in blood pressure. The most common symptoms are nausea, light-headedness, and sweating. The heart rate commonly increases as the body tries to compensate for the lowered blood pressure. By lying on the left side, the pressure on the vena cava is relieved and the blood pressure usually returns to normal and light-headedness ceases.

If a pregnant woman experiences inferior vena cava syndrome, it is often best for her to avoid lying on her back and instead lie on the side.