Umbilical Cord Plasma Interleukin-6 Concentrations in Preterm Infants and Risk of Neonatal Morbidity

Objective: This study was undertaken to evaluate the association between umbilical cord interleukin-6 (IL-6) levels and neonatal morbidity in infants born at less than 32 weeks' gestation.

Study Design: Umbilical cord plasma IL-6 levels and neonatal outcomes were assessed in 309 infants born between 24 weeks and 0 days' and 31 weeks and 6 days' gestation.

Results: Mean IL-6 levels were higher in spontaneous (n = 193, 355 +/- 1822 pg/mL) compared with indicated preterm births (n = 116, 37 +/- 223 pg/mL, P < .0001). Adjusting for gestational age, a progressive relationship was noted between increasing IL-6 levels and increased risk of neonatal systemic inflammatory response syndrome (SIRS). IL-6 levels beyond the 90th percentile (> or =516.6 pg/mL) were also significantly associated with periventricular leukomalacia (PVL; odds ratio [OR] 15, 95% CI 2-149) and necrotizing enterocolitis (NEC; OR 6, 95% CI 1.1-33). In the multivariate analysis, an IL-6 level 107.7 pg/mL or greater (determined by receiver operating curve analysis) remained a significant independent risk factor for PVL (OR 30.3, 95% CI 4.5-203.6).

Conclusion: Umbilical cord IL-6 levels are higher in preterm infants born after spontaneous preterm labor or premature rupture of membranes. Elevated IL-6 levels are associated with an increased risk for SIRS, PVL, and NEC in infants born at less than 32 weeks' gestation.