title: Timing of antenatal corticosteroid administration and survival in extremely preterm infants: a national population-based cohort study.
abstract: OBJECTIVE
  To explore the association between administration-to-birth interval of antenatal corticosteroids (ACS) and survival in extremely preterm infants.
  
  
  METHODS
  Population-based prospective cohort study.
  
  
  METHODS
  All obstetric and neonatal units in Sweden from 1 April 2004 to 31 March 2007.
  
  
  METHODS
  All live-born infants (n = 707) born at 22-26 completed weeks of gestation.
  
  
  METHODS
  The relationship between time from first administration of ACS to delivery and survival was investigated using Cox proportional hazards regression analysis.
  
  
  METHODS
  Neonatal (0-27 days) and infant (0-365 days) survival, and infant survival without major neonatal morbidity (intraventricular haemorrhage grade ≥ 3, retinopathy of prematurity stage ≥ 3, periventricular leukomalacia, necrotising enterocolitis, or severe bronchopulmonary dysplasia).
  
  
  RESULTS
  Five-hundred and ninety-one (84%) infants were exposed to ACS. In the final adjusted model, infant survival was lower in infants unexposed to ACS [hazard ratio (HR) = 0.26; 95% confidence interval 0.15-0.43], in infants born <24 h [HR = 0.53 (0.33-0.87)] and >7 days after ACS [HR = 0.56 (0.32-0.97)], but not in infants born 24-47 h after ACS [HR = 1.60 (0.73-3.50)], as compared with infants born 48 h to 7 days after administration. The findings were similar for neonatal survival. Survival without major neonatal morbidity among live-born infants was 14% in unexposed infants and 30-39% in steroid-exposed groups, indicating that any ACS exposure was valuable.
  
  
  CONCLUSIONS
  Administration of ACS 24 h to 7 days before extremely preterm birth was associated with significantly higher survival than in unexposed infants and in infants exposed to ACS at shorter or longer administration-to-birth intervals.
  
  
  CONCLUSIONS
  Timing of antenatal corticosteroids is important for extremely preterm infants' survival.
authors.affiliation: Department of Clinical Science, Intervention and Technology, Division of Pediatrics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Norberg
authors.affiliation: Department of Clinical Science, Intervention and Technology, Division of Pediatrics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Kowalski
authors.affiliation: Department of Obstetrics and Gynecology, Clinical Sciences, Lund University, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Maršál
authors.affiliation: Department of Clinical Science, Intervention and Technology, Division of Pediatrics, Karolinska Institutet, Stockholm, Sweden.|Department of Neonatal Medicine, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Norman
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000209:etiology / Q000401:mortality*; D008297:Male; D011247:Pregnancy; D047928:Premature Birth / Q000188:drug therapy* / Q000401:mortality*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012044:Regression Analysis; D013548:Sweden; D013997:Time Factors
chemical_list: D000305:Adrenal Cortex Hormones
keywords: Administration-to-birth interval; antenatal glucocorticoids; extremely preterm birth; major neonatal morbidity; mortality