Umbilical cord interleukin-6 levels are elevated in term neonates with perinatal asphyxia

Background A correlation between elevation of pro-inflammatory cytokines and white matter injury or abnormal neurologic outcome has been established in the preterm infant. In the full-term neonate, few studies exist linking elevation of cytokines with encephalopathy and poor neurodevelopmental outcome. Our aims were to investigate if serum interleukin-6 concentrations in delivering mothers and their offspring at birth are associated with perinatal asphyxia, and to examine the relation of interleukin-6 levels to the severity of hypoxic-ischemic encephalopathy and to the neurological outcome. Design and methods Serum interleukin-6 levels were measured at birth, 24 and 48 h of life in 50 consecutive term uninfected newborns with perinatal asphyxia and 113 randomly selected healthy term newborns, and at delivery in their mothers. Results The median cord interleukin-6 concentrations in the infants who developed hypoxic-ischemic encephalopathy was 376-fold as high as the values in the normal infants (P < 0.0001) and 5.5-fold as high as those in the infants with asphyxia who did not develop hypoxic-ischemic encephalopathy (P < 0.05). There was also a significant relationship between interleukin-6 and the degree of hypoxic-ischemic encephalopathy, and between interleukin-6 and neurodevelopmental outcome at 2 years of age. Regardless of outcome, in the asphyxiated infants the interleukin-6 values were significantly lower at both 24 and 48 h of life than at birth, with a significant decline from 24 to 48 h of life. Among mothers of the asphyxiated neonates, there were no significant differences in interleukin-6 concentrations between those delivering neonates with and without hypoxic-ischemic encephalopathy. Conclusions Measurement of IL-6 concentrations in the umbilical cord of neonates with perinatal asphyxia may be useful to identify early, and in a relatively simple way, those who are most likely to have subsequent brain injury and adverse outcome.