Objective: The purpose of this study was to test the hypothesis that a systemic fetal inflammatory response is a risk factor for the subsequent development of bronchopulmonary dysplasia in preterm neonates.
Study design: The relationship between interleukin 6 concentrations in umbilical cord plasma at birth and the occurrence of bronchopulmonary dysplasia was examined in 203 preterm births (25-34 weeks). Ninety-six patients underwent transabdominal amniocentesis within 5 days of birth. The relationship between umbilical cord plasma interleukin 6 concentration and bronchopulmonary dysplasia was compared with the relationship between amniotic fluid interleukin 6 concentration and bronchopulmonary dysplasia. Interleukin 6 was measured by specific immunoassay. Logistic regression was used for statistical analysis.
Results: Bronchopulmonary dysplasia was diagnosed in 17% (34/203) of the infants. Neonates in whom bronchopulmonary dysplasia developed had a significantly higher median interleukin 6 concentration in umbilical cord plasma at birth than did those in whom bronchopulmonary dysplasia did not develop (median, 68.3 pg/mL and range, 0.3-6150.0 pg/mL vs median, 6.9 pg/mL and range 0-19,230.0 pg/mL; P <.001). This difference remained significant after adjustment for gestational age at birth (odds ratio, 4.2; 95% confidence interval, 1.6-11.2). Logistic regression analysis indicated that an elevated umbilical cord plasma interleukin 6 concentration was a better predictor of the development of bronchopulmonary dysplasia than was an elevated amniotic fluid interleukin 6 concentration (P <.005).
Conclusion: An elevated interleukin 6 concentration in umbilical cord plasma at birth is an independent risk factor for the development of bronchopulmonary dysplasia. These data support the concept that the injury responsible for bronchopulmonary dysplasia in a subset of neonates may begin before birth and is associated with the development of a fetal systemic inflammatory response, as determined by plasma concentrations of interleukin 6.