Background and Aims The need for early and accurate prediction of outcome in Hypoxic-Ischemic Encephalopathy (HIE) remains critical. We have previously demonstrated that Interleukin 16 (IL-16) is raised in the umbilical cord blood of infants with moderate and severe HIE and has the potential to be developed as a predictive biomarker. Normal reference ranges for IL-16 in umbilical cord blood have not been previously described. The aim of this study was to determine normative levels of IL-16 in full term neonates using cord blood following uncomplicated deliveries.

Methods Full term infants were recruited as part of an ongoing birth cohort study, the Cork BASELINE Birth Cohort Study. All had cord blood drawn and bio-banked at –80°C, within 3 hours of birth. Samples were chosen based on Apgar scores (≥8 at 1min, ≥9 at 5min), duration of ruptured membranes < 24 h, temperature in labour ≤37°C, gestational age ≥37 weeks and birthweight centile ≥10%. Analysis was performed on plasma EDTA, using ELISA Quantikine® (R&D Systems, Europe).

Results The study consisted of samples from 48 infants with two different modes of delivery; unassisted vaginal delivery (n=12 male, n=12 female) and pre-labour elective caesarean section (n=12 male, n=12 female). The range of all samples was normally distributed between 87.0 and 114.6 pg/ml. Mean (SD) for IL-16 was 103.1 (± 21.9) pg/ml. Levels were not affected by gender or mode of delivery.

Conclusion For the first time we have described the expected range of cord plasma IL-16 levels in healthy term infants.