title: Prenatal exposure to the 1957 influenza epidemic and adult schizophrenia: a follow-up study.
abstract: BACKGROUND
  We investigated the hypothesis that prenatal exposure to the 1957 A2 influenza increases the risk of schizophrenia in adulthood.
  
  
  METHODS
  We traced a cohort of individuals known to have been exposed to the 1957 influenza epidemic during gestation and an unexposed cohort matched for period of gestation and hospital of birth. Follow-up information on psychiatric illness in subjects was sought from two sources: maternal interview and psychiatric hospital admission data.
  
  
  RESULTS
  Follow-up information was obtained on 54% of the sample: 238 subjects from the influenza-exposed group and 287 subjects from the unexposed group. There was no increased risk of schizophrenia among the exposed cohort compared to the unexposed cohort (relative risk 1.1; 95% Cl 0.41-2.95), although there was an increase in depressive illness (relative risk 1.59; 95% Cl 1.15-2.19).
  
  
  CONCLUSIONS
  The association between prenatal influenza and an increased risk of schizophrenia in adulthood has thus far been found only in population-based data and is not supported by the present observational study which has information about exposure and outcome in individuals.
authors.forename: M
authors.initials: M
authors.lastname: Cannon
authors.forename: D
authors.initials: D
authors.lastname: Cotter
authors.forename: V P
authors.initials: VP
authors.lastname: Coffey
authors.forename: P C
authors.initials: PC
authors.lastname: Sham
authors.forename: N
authors.initials: N
authors.lastname: Takei
authors.forename: C
authors.initials: C
authors.lastname: Larkin
authors.forename: R M
authors.initials: RM
authors.lastname: Murray
authors.forename: E
authors.initials: E
authors.lastname: O'Callaghan
mesh_terms: D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology*; D007494:Ireland / Q000453:epidemiology; D011247:Pregnancy; D011295:Prenatal Care; D011297:Prenatal Exposure Delayed Effects; D012189:Retrospective Studies; D012559:Schizophrenia / Q000209:etiology*