Anemia is a shortage of red blood cells. Since red blood cells carry oxygen throughout the body, anemia can deprive the body of needed oxygen. Low oxygen levels (oxygenation) in a premature infant can lead to medical complications or make complications worse.

Common causes of anemia in premature infants include:

• Blood loss from repeat blood draws and testing.
• Inability to produce enough red blood cells, causing "anemia of prematurity." Around the time of the due date, the infant's body becomes mature enough to produce sufficient red blood cells, and the anemia improves.

Mild anemia may not require treatment. More severe anemia is treated with blood transfusions or with a medicine (erythropoietin) that improves the body's ability to produce red blood cells.