The relationship between eosinophilia and bronchopulmonary dysplasia in premature infants at less than 34 weeks' gestation.

Purpose: Eosinophilia is common in premature infants, and its incidence increases with a shorter ges­ tation period. We investigated the clinical significance of eosinophilia in premature infants born at 3% of the total leukocytes. Perinatal parameters and clinical parameters were also analyzed. Results: Of the 261 infants born at <34 weeks gestation, 22.4% demonstrated eosinophilia at birth. The eosinophil percentage peaked in the fourth postnatal week at 7.5%. The incidence of severe eosi­ nophilia increased after birth up to the fourth postnatal week when 8.8% of all patients had severe eosi­ nophilia. Severity of eosinophilia was positively correlated with a lower gestational age, birth weight, and Apgar score. Respiratory distress syndrome, bronchopulmonary dysplasia, nephrocalcinosis, intraventricular hemorrhage, and sepsis were associated with a higher eosinophil percentage. The eosinophil percentage was significantly higher in infants with bronchopulmonary dysplasia from the first postnatal week and the percentage was the highest in the fourth postnatal week, with the maximal difference being 4.1% (P<0.001). Conclusion: Eosinophilia is common in premature infants and reaches peak incidence and severity in the fourth postnatal week. The eosinophil percentage was significantly higher in bronchopulmonary dysplasia patients from the first postnatal week. Severe eosinophilia was significantly associated with the incidence of bronchopulmonary dysplasia even after adjusting for other variables.