Procalcitonin (PCT) is a calcitonin prohormone secreted from the parenchymal tissues. This marker of inflammation has been shown to be a valuable diagnostic marker for bacterial infection in adults and in children. It also seems to be a reliable marker for neonatal bacterial infection, which would make it useful in the detection of EONI. Because physiological levels of PCT vary during the first days of life, possibly due to postnatal intestinal bacterial colonization, levels of this marker are difficult to interpret in the early neonatal period. However, in a study of 2151 newborns with suspected EONI, Nicolas Joram et al. found that PCT obtained from the umbilical blood cord, prior to newborn intestinal colonization, bypasses this postnatal physiological peak of PCT and effectively constitutes a discriminant marker to distinguish between infected and healthy infants using a cutoff value of 0.6 ng/ml.