title: Daily mortality of infants born at less than 30weeks' gestation.
abstract: Few studies have reported odds of mortality for hospitalized premature infants stratified by postnatal age and adjusted for severity of illness. Our objective was to examine day-by-day mortality of premature infants in a large multicenter cohort of infants, adjusted for demographics, severity of illness, and receipt of therapeutic interventions.
  
  
  
  This was a multicenter cohort study of infants cared for in 362 neonatal intensive care units with a shared clinical data warehouse from 1997 to 2013. We included all inborn infants born at 22-29weeks' gestational age with available mortality discharge data. We report the point prevalence of survival to hospital discharge stratified by gestational and postnatal age.
  
  
  
  We identified 64,896 infants, of whom 55,348 (85%) survived to hospital discharge. Survival increased with gestational and postnatal age, until infants reached a postmenstrual age of approximately 37weeks, after which survival began to decrease. Overall survival increased over time (80% in 1997 to 88% in 2013, P<.001).
  
  
  
  Given the known association between gestational age and postnatal age, survival predictions should be adjusted for both covariates.
authors.affiliation: Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States; Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, United States.
authors.forename: Christoph P
authors.initials: CP
authors.lastname: Hornik
authors.affiliation: Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States; Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, United States.
authors.forename: Ashley L
authors.initials: AL
authors.lastname: Sherwood
authors.affiliation: Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States.
authors.forename: C Michael
authors.initials: CM
authors.lastname: Cotten
authors.affiliation: Department of Pediatrics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Laughon
authors.affiliation: Pediatrix-Obstetrix Center for Research and Education, Sunrise, FL, United States.
authors.forename: Reese H
authors.initials: RH
authors.lastname: Clark
authors.affiliation: Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States; Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, United States. Electronic address: brian.smith@duke.edu.
authors.forename: P Brian
authors.initials: PB
authors.lastname: Smith
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D008297:Male; D016019:Survival Analysis
keywords: Gestational age; Mortality; Premature infant