title: Do firstborn children have an increased risk of ADHD?
abstract: OBJECTIVE
  Although previous reports have found no birth-order influence on ADHD risk, the authors hypothesize that being the firstborn is a risk factor for developing ADHD.
  
  
  METHODS
  They selected all of the currently treated ADHD outpatients (n = 748) from our database. Families with adopted sons, nonnuclear families, and families with only one child and with sons (affected or unaffected) younger than 6 or older than 18 years were excluded. A total of 181 families with 213 ADHD sons met the inclusion criteria. We used all siblings without a clinical diagnosis of ADHD and who had no contact with our service as our unaffected controls (n = 173).
  
  
  RESULTS
  The bivariate analysis showed that ADHD was associated with birth order and that firstborn children had nearly twice the ADHD risk of children with other birth orders.
  
  
  CONCLUSIONS
  birth order can be an ADHD risk factor in clinical samples.
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain masanaa@peremata.com.
authors: Adela Masana
authors: AM
authors: Marín
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain.
authors: Fernando Lopez
authors: FL
authors: Seco
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain.
authors: Susana Martí
authors: SM
authors: Serrano
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain.
authors: Silvia Acosta
authors: SA
authors: García
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain.
authors: Ana Milena
authors: AM
authors: Gaviria Gómez
authors: Child and Adolescent Mental Health Centers. Pere Mata Group, IISP, Universitat Rovira i Virgili, Spain.
authors: Inti
authors: I
authors: Ney
mesh_terms: D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology; D001722:Birth Order / Q000523:psychology*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D010290:Parents; D015995:Prevalence; D012307:Risk Factors; D035781:Siblings / Q000523:psychology*