 Exposure For the primary analyses two groups of babies with neonatal sepsis will be considered: those with proven sepsis and those with suspected sepsis. Sepsis will be considered proven when pathogenic organisms i.e. bacteria or fungi were cultured from blood andor cerebrospinal fluid. All babies with clinical neonatal sepsis in whom cultures remained negative are considered to have suspected sepsis. In a secondary analysis, neurodevelopmental outcomes of babies with proven sepsis will be compared to those with suspected sepsis according to causative organism grouped as follows: coagulase-negative staphylococci CONS; other Gram-positive bacteria; Gram-negative bacteria; fungi. Babies will be classified according to the sepsis episode at the time of inclusion in the INIS trail. The impact of any additional episodes of sepsis will be investigated in sensitivity analyses see below. 