Anemia of prematurity

Premature babies are especially at risk for anemia, a deficiency of red blood cells. While the severity of anemia varies, it is usually successfully treated. Treating anemia of prematurity can prevent long-term negative effects on growth, development and neurologic function.

In adults and babies alike, new RBCs are constantly being produced in the bone marrow and old ones broken down in the body. This process tends to occur in cycles, so there can be more or fewer red blood cells than average in the body at any given time. For premature babies, this cycle of red cell breakdown is usually more pronounced, and red cell production may be slower due to immature bone marrow.

Typically, a premature baby will have a normal decrease in RBCs a few days or weeks after birth. Additionally, premature babies often need to have blood drawn for other tests, sometimes frequently. Although the amount of blood taken from a newborn baby will be the absolute minimum, anemia can be caused or can be made more severe simply by this process of blood test collection.

How anemia of prematurity is diagnosed

Although mild anemia is not particularly dangerous, severe anemia can be serious, as red blood cells are responsible for the transport of oxygen throughout the body. Severe anemia can affect overall growth, neurologic and cardiac function, and contribute to complications such as necrotizing enterocolitis (NEC). Over a period of weeks, a premature baby with anemia of prematurity will likely appear pale and lethargic, though occasionally there will be no symptoms. Blood work will be obtained, specifically a hemoglobin level and a reticulocyte count, which gives an indication of how fast RBCs are being produced and released into the bloodstream.

How anemia of prematurity is treated

There are several effective ways of preventing or reducing the severity of anemia of prematurity:

• delayed clamping of the umbilical cord at birth
• reducing the frequency and volume of blood tests
• early iron supplementation

A baby with anemia of prematurity requires iron supplements, since iron is essential for red blood cell production. Iron supplements are started when the baby is mature enough to tolerate feeds. After iron supplementation, the desired increase in red blood cell production will take several weeks. Iron supplementation is recommended for premature infants for the first six to 12 months of life.

The usual treatment of severe anemia is with blood transfusions to replace the depleted red blood cells. The decision to transfuse an infant with red blood cells will depend on many factors, including their age, need for respiratory support, and overall clinical stability. Premature babies commonly require blood transfusions for anemia. In special circumstances, babies may be given medications that stimulate the production of red blood cells called ESAs, or erythropoiesis-stimulating agents.

References

Canadian Paediatric Society (2020). Position statement: Red blood cell transfusion in newborn infants. Retrieved from: https://cps.ca/documents/position/red-blood-cell-transfusion-newborn-infants

Canadian Paediatric Society (2019). Practice point: Iron requirements in the first 2 years of life. Retrieved from: https://cps.ca/documents/position/iron-requirements