title: Late-preterm birth and neonatal morbidities: population-level and within-family estimates.
abstract: OBJECTIVE
  The objective of this study was to compare two salient neonatal outcomes-respiratory disorders and hyperbilirubinemia-between late-preterm (34-36 weeks) and full-term (37-41 weeks) singleton infants both at the population level and within families.
  
  
  METHODS
  Analyses were based on natality data on all births in the state of New Jersey from 1996 to 2006 linked to newborn hospital discharge records. For population-level models, logistic regression analyses were conducted to estimate unadjusted and adjusted differences in outcomes by gestational age. For within-family analyses, unadjusted and adjusted logistic fixed-effects models were estimated with the latter including factors that differed across births to the same mother.
  
  
  RESULTS
  Late-preterm birth increased the odds of a neonatal respiratory condition by more than fourfold (odds ratio, 4.08-4.53) and of neonatal hyperbilirubinemia by more than fivefold (odds ratio, 5.11-5.93) even when comparing births to the same mother and controlling for demographic and economic, behavioral, and obstetric factors that may have changed across pregnancies.
  
  
  CONCLUSIONS
  Based on population-level and within-family models, this study provides the strongest evidence to date that late-preterm birth is an important risk factor for adverse neonatal outcomes that other studies have found are associated with cognitive and behavioral disorders in childhood.
authors.affiliation: Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ. Electronic address: nancy.reichman@rwjms.rutgers.edu.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Reichman
authors.affiliation: School of Social Work, Columbia University, New York, NY.
authors.forename: Julien O
authors.initials: JO
authors.lastname: Teitler
authors.affiliation: Department of Sociology, Princeton University, Princeton, NJ.
authors.forename: Sophie
authors.initials: S
authors.lastname: Moullin
authors.affiliation: Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ.
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Ostfeld
authors.affiliation: Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hegyi
mesh_terms: D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D006932:Hyperbilirubinemia / Q000453:epidemiology* / Q000208:ethnology; D007231:Infant, Newborn; D007234:Infant, Premature; D009017:Morbidity; D009515:New Jersey / Q000453:epidemiology; D047928:Premature Birth / Q000453:epidemiology* / Q000208:ethnology; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology* / Q000208:ethnology; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors
keywords: Late preterm; Near term; Neonatal hyperbilirubinemia; Neonatal jaundice; Neonatal morbidities; Neonatal respiratory conditions; Within-family analyses