Relative neutrophils (cord blood)

This test measures the percentage of neutrophils, a type of white blood cell, in a sample of umbilical cord blood collected immediately after birth. Neutrophils are key defenders against bacterial infections, and the result reflects how large a share of all white blood cells are neutrophils at that moment.

It is typically performed as part of a complete blood count with differential for a newborn. Clinicians use it to understand the baby’s immune and inflammatory status at birth, especially if there were concerns during pregnancy or delivery, or if the baby needs closer evaluation for possible infection.

The relative neutrophil percentage can help your baby’s care team evaluate the likelihood of infection or inflammation and guide decisions about monitoring and treatment. A higher or lower proportion of neutrophils can occur with stress around delivery, early infection, or other medical conditions that affect how white blood cells are produced or used.

On its own, this result is not diagnostic. It is interpreted together with your baby’s exam, medical history, and other tests, such as the absolute neutrophil count, the presence of immature white cells, and infection markers. This combined picture helps decide whether simple observation, repeat testing, or antibiotics are appropriate.

Your baby’s result is interpreted in the context of gestational age, how the delivery went, maternal medications, and when the sample was collected. Newborn white blood cell patterns naturally change around birth, so timing matters for understanding what a result means.

A higher proportion of neutrophils can be seen with infection, inflammation, or physiologic stress. A lower proportion can occur if neutrophils are being used up, if production is temporarily limited, or if other white cell types are relatively increased. If the result raises concern, the team may repeat the test, look at the absolute neutrophil count and immature-to-total ratio, order infection markers, or perform cultures. Your clinician will explain next steps and whether any treatment is needed.