Neutropenia is an abnormally low number of white blood cells called neutrophils. Neutrophils help the body fight infection. This article discusses neutropenia in infants.

Neutrophils are produced in the bone marrow and released into the bloodstream to travel to wherever they are needed. Low levels of neutrophils occur when the bone marrow cannot replace them as fast as needed. A very severe infection may also prevent the bone marrow from producing more neutrophils.

In babies, the most common cause of neutropenia is infection.

Occasionally, an infant who is not sick will have a low neutrophil count for no apparent reason. Some disorders in the pregnant mother, such as preeclampsia, can also lead to neutropenia in infants.

A small sample of the baby's blood will be sent to the laboratory for a complete blood count (CBC) and blood differential. A CBC reveals the number and type of cells in the blood. The differential helps determine the number of different types of white blood cells in a blood sample.

The source of the infection should be identified and treated.

In many cases, nonsevere neutropenia goes away on its own as the bone marrow recovers and begins to produce enough white blood cells.

In rare cases when the neutrophil count is low enough to be life threatening, the following treatments may be recommended:

• Medicines to stimulate white blood cell production
• Antibodies from donated blood samples (intravenous immune globulin)

The outcome of the baby depends on the underlying cause of the neutropenia. Some infections in newborns can be life threatening. However, most infections usually do not cause long-term side effects after the neutropenia goes away or is successfully treated.