AREG and infection: Given that prevalence declines with advancing birth gestation, the negative predictive value of this combined test is likely to be even higher in babies born >28 weeks or ≥ 30 weeks GA respectively, in whom the prevalence of late-onset suspected or confirmed infection has been estimated at 22% and 8% (NPV of combined amphiregulin/CRP test if prior probability of infection is 0.22 = 0.99; Supplementary Fig. 8c)1.