About the data: We used the family income data from the 2013 American Community Survey. This counts only families, which the government defines as households with two or more people related by birth, marriage or adoption. The graph focuses on families living in the country's 30 most populous cities.
The higher pressure causes swelling in the legs and feet. Congestive heart failure, a condition in which the heart can no longer pump efficiently, causes fluid buildup in the lungs and other parts of the body. Swelling is often most visible in the feet and ankles. Pregnancy can cause edema in the legs as the uterus puts pressure on the vena cava, a major blood vessel that returns blood to the heart from the legs. Fluid retention during pregnancy also can be caused by a more serious condition called preeclampsia.
Swelling of the foot, ankle and leg can be severe enough to leave an indentation (pit) when you press on the area. This swelling (edema) is the result of excess fluid in your tissues â often caused by congestive heart failure or blockage in a leg vein.