title: Autism with intellectual disability related to dynamics of head circumference growth during early infancy.
abstract: BACKGROUND
  It is not yet definitively known whether dynamic features of head circumference growth are associated with autism. To address this issue, we carried out a nested matched case-control study using data from national well baby clinics in Finland; autism cases were identified from the Finnish Hospital and Outpatient Discharge Registry.
  
  
  METHODS
  A nonparametric Bayesian method was used to construct growth velocity trajectories between birth and 2 years of age in autism cases and matched control subjects (n = 468 in main analyses, 1:1 matched control subjects). Estimates of odds ratios for autism risk in relation to the growth velocities were obtained using conditional logistic regression.
  
  
  RESULTS
  Growth velocity of head circumference at 3 months of age, adjusting for gestational age at birth and maternal age, is significantly associated with autism (p = .014); the finding was observed in subjects with comorbid intellectual disability (ID) (p = .025) but not in those without ID (p = .15). Height growth velocity among subjects with autism and without ID is significantly associated with autism at 6 months (p = .007), and weight growth velocity at 18 months without ID (p = .02) and 24 months without ID (p = .042) and with ID (p = .037).
  
  
  CONCLUSIONS
  Acceleration in head circumference growth is associated with autism with comorbid ID at 3 months but not subsequently. This association is unrelated to acceleration in height and weight, which are not strongly associated with autism until after 6 months.
authors.affiliation: Department of Biostatistics, Columbia University Mailman School of Public Health.
authors.forename: Ian W
authors.initials: IW
authors.lastname: McKeague
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute; Department of Epidemiology, Columbia University Mailman School of Public Health, New York, New York.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Brown
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Bao
authors.affiliation: Department of Child Psychiatry, Faculty of Medicine, University of Turku, Turku, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Hinkka-Yli-Salomäki
authors.affiliation: Department of Child Psychiatry, Faculty of Medicine, University of Turku, Turku, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Huttunen
authors.affiliation: Department of Child Psychiatry, Faculty of Medicine, University of Turku, Turku, Finland. Electronic address: andsou@utu.fi.
authors.forename: Andre
authors.initials: A
authors.lastname: Sourander
mesh_terms: D001321:Autistic Disorder / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology; D001499:Bayes Theorem; D001827:Body Height; D001835:Body Weight; D016022:Case-Control Studies; D002657:Child Development; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005387:Finland; D005865:Gestational Age; D006257:Head / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008423:Maternal Age; D009929:Organ Size
keywords: Autism; Development; Epidemiology; Growth Velocity; Head Circumference; Trajectories