B2M and Sepsis: The objectives of this study were: (1) to determine whether levels of CSF B2M were elevated in very preterm and extremely preterm infants with CNS infections or other inflammatory processes, and (2) to determine if there were differences in CSF B2M concentrations between various inflammatory settings (sepsis, meningitis, and progressive post-hemorrhagic ventricular dilatation (PHVD)) in very preterm and extremely preterm infants.