ABSTRACT
OBJECTIVE: The objective of this study was to evaluate the association between empirical antibiotic therapy in the first postnatal week in uninfected infants born very preterm and the risk of adverse outcomes until discharge. STUDY DESIGN: Population-based, nationwide registry study in Norway including all live-born infants with a gestational age <32 weeks surviving first postnatal week without sepsis, intestinal perforation, or necrotizing enterocolitis (NEC) between 2009 and 2018. Primary outcomes were severe NEC, death after the first postnatal week, and/or a composite outcome of severe morbidity (severe NEC, severe bronchopulmonary dysplasia [BPD], severe retinopathy of prematurity, late-onset sepsis, or cystic periventricular leukomalacia). The association between empirical antibiotics and adverse outcomes was assessed using multivariable logistic regression models, adjusting for known confounders. RESULTS: Of 5296 live-born infants born very preterm, 4932 (93%) were included. Antibiotics were started in first postnatal week in 3790 of 4932 (77%) infants and were associated with higher aOR of death (aOR 9.33; 95% CI: 1.10-79.5, P = .041), severe morbidity (aOR 1.88; 95% CI: 1.16-3.05, P = .01), and severe BPD (aOR 2.17; 95% CI: 1.18-3.98; P = .012), compared with those not exposed. Antibiotics ≥ 5 days were associated with higher odds of severe NEC (aOR 2.27; 95% CI: 1.02-5.06; P = .045). Each additional day of antibiotics was associated with 14% higher aOR of death or severe morbidity and severe BPD. CONCLUSIONS: Early and prolonged antibiotic exposure within the first postnatal week was associated with severe NEC, severe BPD, and death after the first postnatal week.