title: Preterm birth and behavioural outcomes at 8 years of age: a nationwide survey in Japan.
abstract: OBJECTIVE
  To analyse the effect of different preterm birth categories on behavioural outcomes.
  
  
  METHODS
  Prospective cohort design.
  
  
  METHODS
  The Japanese Longitudinal Survey of Babies in the 21st Century was used for the study.
  
  
  METHODS
  Neonates born in 2001 in Japan (n=34,163) and followed up at the age of 8 years. Post-term births were excluded and the sample was divided into four groups according to gestational age: <34 weeks, 34-36 weeks, 37-38 weeks and 39-41 weeks.
  
  
  METHODS
  Seven behavioural outcomes were examined: three attention problems and four delinquent/aggressive behaviours.
  
  
  RESULTS
  Logistic regression was used to estimate adjusted ORs and 95% CIs for each outcome. Positive associations were found between preterm birth (<37 weeks) and adverse behavioural outcomes compared with full-term birth (39-41 weeks). For attention problems, the OR for 'inability to wait his/her turn' was increased by 1.72 (95% CI 1.22 to 2.43) for gestational age <34 weeks and by 1.28 (95% CI 1.03 to 1.59) for 34-36 weeks' gestation. For delinquent/aggressive behaviour, the OR for the outcome 'destroying books/toys' was increased by 1.46 (95% CI 1.07 to 1.99) for gestational age <34 weeks, while the outcome 'disturbance in public' was increased by 1.20 (95% CI 1.04 to 1.38) for 34-36 weeks' gestation.
  
  
  CONCLUSIONS
  Children who are born <34 weeks, but also between 34 and 36 weeks, are at increased risk of behavioural problems related to attention and delinquent/aggressive behaviour when 8 years old.
authors.affiliation: Department of Human Ecology, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
authors.forename: Midory
authors.initials: M
authors.lastname: Higa Diez
authors.affiliation: Department of Human Ecology, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yorifuji
authors.affiliation: Department of Psychology, Faculty of Letters, Kansai University, Osaka, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kado
authors.affiliation: Department of Special Education, Faculty of Education, Okayama University, Okayama, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sanada
authors.affiliation: Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Doi
mesh_terms: D002648:Child; D002653:Child Behavior Disorders / Q000453:epidemiology* / Q000209:etiology; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D017063:Outcome Assessment, Health Care; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors
keywords: Attention; Behavior; Delinquent/aggressive behavior; Gestational age; Preterm Birth