Edema occurs as a result of fluid buildup in the tissues due to a number of different causes. Leakage of fluids into body spaces may occur because of increased pressure within the circulatory system, blockages in blood flow, decrease in albumin (protein) levels in the blood, or damage to tissues. Edema may occur during pregnancy. It may also be caused by heart disease (congestive heart failure), kidney disease, cirrhosis (scarring of the liver), and tissue damage such as burns. Excess sodium intake can also increase the amounts of fluid retained by the kidneys and increase fluid pressure, causing the leakage of fluid into the tissue spaces.