 For the primary analysis of this study, only the neonatal sepsis episode at presentation i.e. at inclusion in the INIS trial will be considered to classify babies as having suspected or proven sepsis. An important subgroup of babies however, experienced one or more additional episodes of sepsis following inclusion in the study, which may affect the findings depending on whether or not these were culture-proven. The investigators will therefore undertake two additional sensitivity analyses to assess the impact of subsequent episodes of sepsis on the difference in neurodevelopmental outcome according to whether or not proven sepsis was present. In a first sensitivity analysis the investigators will exclude from the cohort all babies in whom additional episodes of neonatal sepsis were present following the initial presentation with sepsis. This will facilitate a fair comparison of babies with single episodes of proven versus suspected sepsis. In a second sensitivity analysis of the full cohort, the investigators will re-classify as proven sepsis all babies labeled as suspected sepsis based on the initial presentation, in whom subsequent episodes of proven sepsis were present. The investigators will then compare neurodevelopmental outcomes according to whether or not proven sepsis was present at any time point during initial hospital admission. 