Anemia and digestive tract complications are common problems in Extremely Low Birth Weight infants. Anemia is a condition in which the body does not have enough red blood cells (RBC). RBCs are important because they contain hemoglobin, the substance that carries oxygen throughout the body. Transfusions of RBCs in these infants is frequently required to correct the anemia. Oxygen levels in the digestive tract will be measured before, during and after each blood transfusion using a tissue oxygen monitor called Near Infrared Spectroscopy (NIRS). By using this technology, better understanding can be obtained of intestinal blood flow patterns.