IL18 and bronchopulmonary dysplasia: For a better prediction of BPD, a combined analysis of serum IGF-1 concentration and serum IL-18 concentration on day 14 was conducted in Table 4 and Figure 6C: the sensitivity was 91.07% and the specificity was 83.33%, with the AUC of 0.9142, which demonstrated more substantial predictive power than that in a single variable included analysis.