Most hospitalized preterm infants receive antibiotics (AB) in the first days of life to treat or prevent systemic infections. Short-term, early AB treatment may also prevent against the microbiota-dependent serious gut disorder, necrotising enterocolitis (NEC). However, it remains a challenge to predict or early detection of NEC in the first weeks of life and few diagnostic markers exist. Using preterm piglets as models for infants, we hypothesised that proteomic profiling could be used to identify new early plasma biomarkers of NEC with or without prior AB treatment. Preterm newborn pigs were treated with saline (CON) or antibiotics (ampicillin, gentamicin, and metronidazole), given enterally (ENT) or parenterally (PAR), and fed formula for four days to induce NEC. The gut was collected for scoring of NEC lesions and blood was collected for haematology and plasma proteomics