What Is Anemia in Preterm Infants?

Anemia is a lack of red blood cells in the body.
Anemia is a lack of red blood cells in the body. Image courtesy of A.D.A.M.

Question: What Is Anemia in Preterm Infants?

Doctors say my baby is anemic. What does that mean? What are the symptoms of anemia in infants, and how is it treated?


Anemia is a lack of red blood cells. Red blood cells carry oxygen to the body, so infants with anemia have trouble keeping a healthy oxygen saturation.

What Causes Anemia in Preterm Infants?

Most newborn babies have at least mild anemia.

Infants' red blood cells break down faster than new red blood cells are made. Babies are usually at their most anemic around 2 to 3 months old, and gradually improve over the next two years. This normal anemia usually doesn't need any treatment other than a healthy diet with plenty of iron.

Because they are born early, preemies may develop more a more severe type of anemia called anemia of prematurity. In the last weeks of pregnancy, two changes occur that help full-term babies to make red blood cells. First, a lot of the iron needed to make new red blood cells is transferred from the mother to baby in the third trimester. Also, in the last weeks of pregnancy, red blood cell production switches from the liver to the bone marrow. Because the processes that make new red blood cells are immature in preemies, preemies have a higher rate of anemia and their anemia is more severe than in term babies.

NICU care can make anemia in preterm infants worse. Doctors and nurses try to limit the amount of blood that's drawn for lab tests, but even small blood losses can affect very small preemies.

How is Anemia Diagnosed?

Anemia can only be diagnosed through a blood test. If your baby shows symptoms of anemia, doctors may do a blood test to count red blood cells (hemoglobin level) or to look at the percentage of red blood cells in the blood (hematocrit).

These tests are often combined into one blood test, called an "H and H" for hemoglobin level and hematocrit.

What Are the Symptoms of Anemia in Infants?

The symptoms of anemia are subtle and may look like other illnesses, such as infection or respiratory distress. Babies who are anemic may have the following symptoms:

  • Pale color
  • Tachycardia or rapid heart beat
  • Tachypnea, or rapid breathing rate
  • Apnea and bradycardia
  • Poor weight gain
  • Trouble feeding due to tiredness
  • Increased need for oxygen or respiratory support

How is Anemia in Infants Treated?

In term infants, anemia doesn't usually require treatment. As long as a baby gets enough iron through breast milk or iron-fortified foods or formula, normal anemia will get better on its own.

In preemies, anemia may cause enough symptoms that it needs to be treated. A premature baby's anemia may be treated with:

  • Blood transfusion: The fastest way to increase the number of red blood cells in a baby's blood is with a blood transfusion. In a blood transfusion, packed red blood cells from donor blood or from a family member (called a direct donation) are given through an IV line.​
  • Medication: The hormone that causes the body to make more red blood cells is called erythropoietin. We can give a form of erythropoietin, called r-Epo, as a medication that causes the body to make red blood cells. Giving r-Epo can help reduce the number of blood transfusions that a preemie needs, but it takes time to work and is very expensive.


    Von Kohorn, I. & Ehrenkranz, R. March 2009. Anemia in the preterm infant: Erythropoietin versus erythrocyte transfusion - It's not that simple. Clinical Perinatology. 36(1):111-123.

    Widness, J. Pathophysiology of anemia during the neonatal period, including anemia of prematurity. Nov. 2008. Neoreviews. 9(11): e520.

    Continue Reading