Peripheral blood cell counts of prematurely born, small for gestational age neonates

Background: Neonates born small for gestational age (SGA) are at an increased risk of multiple severe complica tions, including infections.This suggests that immune cells and other peripheral blood cells may be affected.Purpose: Here we aimed to investigate whether SGA severity affects complete blood count and leukocyte diffe rentiation of preterm neonates with a gestational age (GA) of <35 weeks and identify clinical factors that influence cell counts.Methods: This retrospective cohort study investigated the complete blood count sampled within 72 hours after birth in 1,940 preterm neonates admitted to the neonatal intensive care unit of Leiden University Medical Center.The neonates were divided into extreme SGA (<3rd birth weight percentile), moderate SGA (>3rd to <10th birth weight percentile), and controls (>10th birth weight per centile).Results: After multivariate analysis, extremely SGA neo nates showed significantly decreased neutrophil, mono cyte, lymphocyte, and thrombocyte counts.Thrombocyte counts were significantly lower in moderately SGA neonates than controls.In contrast, SGA status had no significant effect on erythrocyte count or hemoglobin concentration.Conclusion: Blood cell counts of extremely SGA neona tes were decreased, mainly in the white blood cell line.The mechanisms underlying these decreased counts in SGA infants, especially their clinical effects, remain unclear.