Despite a high prior probability of infection in extremely preterm babies1, a test based on amphiregulin and CRP together demonstrated higher sensitivity (0.97) and negative predictive value (NPV; 0.94; Fig. 6e), compared to tests evaluating CRP (Sensitivity 0.55, NPV 0.65) or amphiregulin alone (Sensitivity 0.88, NPV 0.79; Supplementary Fig. 8b), indicating a potentially greater ability of the combined test to rule-out sepsis. This evidence concerns the gene CRP and infection.