title: Prevalence and neonatal factors associated with autism spectrum disorders in preterm infants.
abstract: OBJECTIVE
  To determine the prevalence of autism spectrum disorders (ASD) across gestational age, examine the risk of ASD by gestational age controlling for other risk factors, and identify potential risk factors in the neonatal intensive care unit.
  
  
  METHODS
  A retrospective cohort of infants born at ≥ 24 weeks between January 1, 2000, and December 31, 2007 at 11 Kaiser Permanente Northern California hospitals (n = 195,021). ASD cases were defined by a diagnosis made at a Kaiser Permanente ASD evaluation center, by a clinical specialist, or by a pediatrician. Cox proportional hazards regression models were used to evaluate the association between gestational age and ASD as well as potential risk factors in the neonatal intensive care unit and ASD.
  
  
  RESULTS
  The prevalence of ASD in infants <37 weeks was 1.78% compared with 1.22% in infants born ≥ 37 weeks (P < .001). Compared with term infants, infants born at 24-26 weeks had an adjusted hazard ratio (HR) for a diagnosis of ASD of 2.7 (95% CI 1.5-5.0). Infants born at 27-33 weeks (adjusted HR 1.4, 95% CI 1.1-1.8) and 34-36 weeks (adjusted HR 1.3, 95% CI 1.1-1.4) were also at increased risk. High frequency ventilation and intracranial hemorrhage were associated with ASD in infants < 34 weeks.
  
  
  CONCLUSIONS
  ASD was ~ 3 times more prevalent in infants <27 weeks compared with term infants. Each week of shorter gestation was associated with an increased risk of ASD. High frequency ventilation and intracranial hemorrhage were associated with ASD among infants <34 weeks.
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA; Division of Neonatology, Department of Pediatrics, University of California-San Francisco, San Francisco, CA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kuzniewicz
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Soora
authors.initials: S
authors.lastname: Wi
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Yinge
authors.initials: Y
authors.lastname: Qian
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Walsh
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Armstrong
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Croen
mesh_terms: D002140:California / Q000453:epidemiology; D002659:Child Development Disorders, Pervasive / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D007236:Infant, Small for Gestational Age; D008297:Male; D015995:Prevalence; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors
keywords: ASD; Autism spectrum disorders; CDER; Client Development and Evaluation Report; DDS; Developmental Services; EDC; Estimated date of confinement; HR; Hazard ratio; ICD-9; ICD-9-CM; ICD-9-clinical modification; ICH; International Classification of Diseases, 9th revision; Intracranial hemorrhage; KP; KPNC; Kaiser Permanente; Kaiser Permanente Northern California; NICU; Neonatal intensive care unit; SGA; Small for gestational age