ObjectivesAntenatal corticosteroids (ACS) decrease neonatal mortality and morbidity among preterm neonates, yet there has been concern regarding their long-term safety. We hypothesised that potential long-term adverse effects of ACS may be observed among infants born during the late preterm period (LPT, 340/7–366/7 weeks of gestation), when the benefits of ACS are subtle.DesignPopulation-based, retrospective cohort.SettingOntario, Canada, between 2006 and 2011.PatientsAll live singleton infants born during the LPT period with a minimum 5-year follow-up.InterventionsExposure to ACS prior to 340/7 weeks of gestation.Main outcome measuresSuspected neurocognitive disorder, audiometry testing or visual testing.ResultsOverall, 25 668 infants were eligible for analysis, of whom 2689 (10.5%) received ACS. Infants in the ACS group had lower mean birth weight and higher rates of birth weight <10th percentile, neonatal resuscitation and neonatal intensive care unit admission. At 5 years of age, ACS exposure was associated with an increased risk of suspected neurocognitive disorder (adjusted HR (aHR) 1.12, 95% CI 1.05 to 1.20), audiometry testing (aHR 1.20, 95% CI 1.10 to 1.31) and visual testing (aHR 1.06, 95% CI 1.01 to 1.11).ConclusionIn children born during the LPT period, exposure to ACS prior to 340/7 weeks of gestation is associated with an increased utilisation of the healthcare system related to audiometry and visual testing and suspected neurocognitive disorders by 5 years of age.
488: Long-term neurobehavioral effects of antenatal corticosteroids in a late preterm rabbit model