title: Are fetal growth impairment and preterm birth causally related to child attention problems and ADHD? Evidence from a comparison between high-income and middle-income cohorts.
abstract: Cross-cohort comparison is an established method for improving causal inference. This study compared 2 cohorts, 1 from a high-income country and another from a middle-income country, to (1) establish whether birth exposures may play a causal role in the development of childhood attention problems; and (2) identify whether confounding structures play a different role in parent-reported attention difficulties compared with attention deficit hyperactivity disorder (ADHD) diagnoses.
  
  
  
  Birth exposures included low birth weight (LBW), small-for-gestational age (SGA), small head circumference (HC) and preterm birth (PTB)). Outcomes of interest were attention difficulties (Strengths and Difficulties Questionnaire, SDQ) and ADHD (Development and Well-Being Assessment, DAWBA). Associations between exposures and outcomes were compared between 7-year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC) in the UK (N=6849) and the 2004 Pelotas cohort in Brazil (N=3509).
  
  
  
  For attention difficulties (SDQ), the pattern of association with birth exposures was similar between cohorts: following adjustment, attention difficulties were associated with SGA (OR=1.59, 95% CI 1.20 to 2.19) and small HC (OR=1.64, 95% CI 1.11 to 2.41) in ALSPAC and SGA (OR=1.35, 95% CI 1.04 to 1.75) in Pelotas. For ADHD, however, the pattern of association following adjustment differed markedly between cohorts. In ALSPAC, ADHD was associated with LBW (OR=2.29, 95% CI 1.09 to 4.80) and PTB (OR=2.33, 95% CI 1.23 to 4.42). In the Pelotas cohort, however, ADHD was associated with SGA (OR=1.69, 95% CI 1.02 to 2.82).
  
  
  
  The findings suggest that fetal growth impairment may play a causal role in the development of attention difficulties in childhood, as similar associations were identified across both cohorts. Confounding structures, however, appear to play a greater role in determining whether a child meets the full diagnostic criteria for ADHD.
authors.affiliation: Section of Child and Adolescent Psychiatry, Department of Psychiatry, Oxford University, Oxford, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Murray
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Pearson
authors.affiliation: Nuffield Department of Obstetrics & Gynaecology, Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Fernandes
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Iná S
authors.initials: IS
authors.lastname: Santos
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil Postgraduate Program in Health and Behavior, Catholic University of Pelotas, Pelotas, Brazil.
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Barros
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Cesar G
authors.initials: CG
authors.lastname: Victora
authors.affiliation: Section of Child and Adolescent Psychiatry, Department of Psychiatry, Oxford University, Oxford, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Stein
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil Department of Preventive Medicine, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Alicia
authors.initials: A
authors.lastname: Matijasevich
mesh_terms: D000368:Aged; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology*; D001938:Brazil; D002648:Child; D005260:Female; D047109:Fetal Development; D005317:Fetal Growth Retardation; D006801:Humans; D007182:Income; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy; D047928:Premature Birth
keywords: Cohort studies; MATERNAL & CHILD CG; PERINATAL EPIDEMIOLOGY