title: Fluctuations in schizophrenic births by year.
abstract: BACKGROUND
  It has previously been reported that births of individuals who later develop schizophrenia vary by birth year.
  
  
  METHODS
  Birth data were analysed on 34,024 individuals diagnosed with DSM-III-R disorganised, catatonic, and undifferentiated schizophrenia using time series analysis.
  
  
  RESULTS
  Minor yearly fluctuations were observed but did not achieve statistical significance. Thus earlier findings reported in the literature could not be replicated using a different statistical approach.
  
  
  CONCLUSIONS
  The findings do not support theories which assume major yearly fluctuations in the births of individuals with schizophrenia. Such theories include the perinatal effects of influenza, temperature variation, and the effects of severe weather.
authors.affiliation: National Institute of Mental Health, Neuroscience Center at St Elizabeths, Washington, DC 20032, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Torrey
authors.forename: R R
authors.initials: RR
authors.lastname: Rawlings
mesh_terms: D000328:Adult; D000368:Aged; D001723:Birth Rate; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D012559:Schizophrenia / Q000145:classification / Q000453:epidemiology* / Q000209:etiology; D012621:Seasons; D014481:United States / Q000453:epidemiology