Hematological parameters in preterm infants in early childhood

The objective of our study was to establish characteristic values of the main hematological parameters (platelet, red blood cell (RBC), and white blood cell (WBC) counts, and hemoglobin level) in preterm infants in early childhood, taking into account their birth weight. The study was approved by the independent Ethics Committee and the Scientific Council of the Siberian State Medical University of Ministry of Healthcare of the Russian Federation (Tomsk). The study included data from 302 children born between 2014 and 2020 in Tomsk. The inclusion criteria for the main study group were premature infants with a birth weight of less than 2500 grams. The main group (n = 226) was stratified by birth weight: low birth weight (n = 78), very low birth weight (n = 76), and extremely low birth weight (n = 72). The inclusion criteria for the control group (n = 76) were healthy full-term infants with a birth weight of more than 2500 grams. During follow-up care for the first three years of life, the following complete blood count parameters were measured in the early neonatal period (initial examination within the first 24 hours of birth), and at the age of one, two, and three years: hemoglobin level (g/L), RBC count (× 10¹²/L), WBC count (× 10⁹/L) and platelet count (× 10⁹/L). Our study showed a correlation of complete blood count parameters with birth weight in children from birth to three years. In the neonatal period, there was a direct correlation between birth weight and RBC count (r = 0.428; p < 0.001), hemoglobin levels (r = 0.137; p = 0.029), and platelet counts (r = 0.453; p < 0.001). In the first days of life, children with extremely low birth weight had statistically significantly lower RBC counts (3.92 (3.51–4.27) × 10¹²/L), platelet counts (171.5 (133–229) × 10⁹/L) and hemoglobin levels (156 (142–172) g/L) than children in other groups. We observed an inverse correlation between hemoglobin level and birth weight and a direct correlation between platelet count and birth weight in early childhood. The study revealed the dependence of some hematological parameters in premature infants on their birth weight, which requires further investigation.