Objective:Determine the association of prenatal and neonatal infections with neurodevelopmental outcomes in very preterm infants.Study Design:Secondary retrospective analysis of 155 very preterm infants at a single tertiary referral center. General linear or logistic regression models were used to evaluate the association with hospital factors; brain injury, growth and development; and neurobehavioral outcome.Result:Necrotizing enterocolitis with sepsis was associated with reduced transcerebellar diameter (38.3 vs 48.4 mm, P<0.001) and increased left ventricular diameter (12.0 vs 8.0 mm, P=0.005). Sepsis alone was associated with higher diffusivity in the left frontal lobe (1.85 vs 1.68 × 10-3 mm 2 s-1, P=0.001) and right cingulum bundle (1.52 vs 1.45 × 10-3 mm 2 s-1, P=0.002). Neurobehavioral outcomes were worse in children exposed to maternal genitourinary infection (cognitive composite: β=-8.8, P=0.001; receptive language score: β=-2.7, P<0.001; language composite: β=-14.9, P<0.001) or histological chorioamnionitis (language composite: β=-8.6, P=0.006), but not neonatal infection.Conclusion:Neonatal infection was associated with changes in brain structure but not with neurobehavioral outcomes, whereas the opposite pattern was observed for maternal genitourinary tract infection. These findings emphasize the potential importance of infections during pregnancy on the neurodevelopmental outcomes of preterm infants.