The purpose of this randomized controlled trial is to evaluate the effect of daily supplementation with a probiotic mixture on the neurodevelopmental outcomes of preterm infants with a history of neonatal antibiotic exposure. The intervention lasts for 6 months. The study hypothesizes that early gut microbiota remodeling via exogenous probiotics can improve neurodevelopment. The primary outcome is assessed by the Gesell Developmental Schedules or the Ages \& Stages Questionnaires (ASQ-3). Secondary outcomes include longitudinal changes in gut microbiota composition,targeted metabolomics (such as short-chain fatty acids \[SCFAs\], and systemic inflammatory markers.