Gestation-wise Reference Ranges of Neutrophil Counts in Indian Newborns

Objectives: Blood counts are commonly performed tests in neonatal intensive care units with the results having various clinical ramifications. Interpreting blood counts as normal or abnormal requires reference ranges as per gestation. Studies on reference ranges for neonatal neutrophil counts are already scarce, and data is lacking in the Asian context. We sought to formulate gestation-wise reference ranges of neutrophil counts in an Indian setting. Methods: Healthy, newborn babies of either gender, aged between 30 to 41 weeks gestation were included in the study. Gestational age was corroborated through first trimester dating scan and postnatally by the New Ballard Score. Single venous blood samples were drawn on day three and day five for estimation of total leukocyte count, differential count (neutrophils, lymphocytes), and peripheral blood smear examination. Results: We evaluated the data of 420 newborns. The normative values were compiled week-wise for gestational ages of 30 to 41 weeks at birth. We observed a clustering of neutrophil count values below 8000 cells/μL on day three and below 5000 cells/μL on day five. No gender-based differences in counts were observed. We were able to generate reference range curves for neutrophil counts as per gestational age. Conclusions: The absolute neutrophil counts of term and preterm Indian newborns are higher than the values depicted in the standard reference chart used currently. This indicates that a different standard chart as per gestation should be used in Indo-Asian countries to differentiate ‘normal’ from ‘abnormal’.