To determine whether use, duration, and types of early antibiotics were associated with neonatal outcomes and late antibiotic use in preterm infants without infection-related diseases.


This cohort study enrolled infants admitted to 25 tertiary NICUs in China within 24 hours of birth during 2015–2018. Death, discharge, or infection-related morbidities within 7 days of birth; major congenital anomalies; and error data on antibiotic use were excluded. The composite outcome was death or adverse morbidities. Late antibiotic use indicated antibiotics used after 7 days of age. Late antibiotic use rate was total antibiotic use days divided by the days of hospital stay after the first 7 days of life.


Among 21 540 infants, 18 302 (85.0%) received early antibiotics. Early antibiotics was related to increased bronchopulmonary dysplasia (BPD) (adjusted odds ratio [aOR], 1.28; 95% confidence interval [CI], 1.05-1.56), late antibiotic use (aOR, 4.64; 95% CI, 4.19-5.14), and late antibiotic use rate (adjusted mean difference, 130 days/1000 patient-days; 95% CI, 112-147). Each additional day of early antibiotics was associated with increased BPD (aOR, 1.07; 95% CI, 1.04-1.10) and late antibiotic use (aOR, 1.41; 95% CI, 1.39-1.43). Broad-spectrum antibiotics showed larger effect size on neonatal outcomes than narrow-spectrum antibiotics. The correlation between early antibiotics and outcomes was significant among noncritical infants but disappeared for critical infants.


Among infants without infection, early antibiotic use was associated with increased risk of BPD and late antibiotic use. Judicious early antibiotic use, especially avoiding prolonged duration and broad-spectrum antibiotics among noncritical infants, may improve neonatal outcomes and overall antibiotic use in NICUs.

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