title: The relationship between eosinophilia and bronchopulmonary dysplasia in premature infants at less than 34 weeks' gestation.
abstract: OBJECTIVE
  Eosinophilia is common in premature infants, and its incidence increases with a shorter gestation period. We investigated the clinical significance of eosinophilia in premature infants born at <34 weeks gestation.
  
  
  METHODS
  We analyzed the medical records of premature infants born at <34 weeks gestation who were admitted to the neonatal intensive care unit at Ewha Womans University Mokdong Hospital between January 2003 and September 2010. Eosinophilia was defined as an eosinophil percentage of >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 eosinophilia increased after birth up to the fourth postnatal week when 8.8% of all patients had severe eosinophilia. 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Joo Yun
authors.initials: JY
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Jihei
authors.initials: J
authors.lastname: Cha
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: So-Yeon
authors.initials: SY
authors.lastname: Shim
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Cho
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Eun Ae
authors.initials: EA
authors.lastname: Park
keywords: Bronchopulmonary dysplasia; Eosinophilia; Premature infants