title: A population-based study of measles, mumps, and rubella vaccination and autism.
abstract: BACKGROUND
  It has been suggested that vaccination against measles, mumps, and rubella (MMR) is a cause of autism.
  
  
  METHODS
  We conducted a retrospective cohort study of all children born in Denmark from January 1991 through December 1998. The cohort was selected on the basis of data from the Danish Civil Registration System, which assigns a unique identification number to every live-born infant and new resident in Denmark. MMR-vaccination status was obtained from the Danish National Board of Health. Information on the children's autism status was obtained from the Danish Psychiatric Central Register, which contains information on all diagnoses received by patients in psychiatric hospitals and outpatient clinics in Denmark. We obtained information on potential confounders from the Danish Medical Birth Registry, the National Hospital Registry, and Statistics Denmark.
  
  
  RESULTS
  Of the 537,303 children in the cohort (representing 2,129,864 person-years), 440,655 (82.0 percent) had received the MMR vaccine. We identified 316 children with a diagnosis of autistic disorder and 422 with a diagnosis of other autistic-spectrum disorders. After adjustment for potential confounders, the relative risk of autistic disorder in the group of vaccinated children, as compared with the unvaccinated group, was 0.92 (95 percent confidence interval, 0.68 to 1.24), and the relative risk of another autistic-spectrum disorder was 0.83 (95 percent confidence interval, 0.65 to 1.07). There was no association between the age at the time of vaccination, the time since vaccination, or the date of vaccination and the development of autistic disorder.
  
  
  CONCLUSIONS
  This study provides strong evidence against the hypothesis that MMR vaccination causes autism.
authors.affiliation: Danish Epidemiology Science Center, Department of Epidemiology and Social Medicine, Arhus, Denmark. kmm@dadlnet.dk
authors.forename: Kreesten Meldgaard
authors.initials: KM
authors.lastname: Madsen
authors.forename: Anders
authors.initials: A
authors.lastname: Hviid
authors.forename: Mogens
authors.initials: M
authors.lastname: Vestergaard
authors.forename: Diana
authors.initials: D
authors.lastname: Schendel
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Poul
authors.initials: P
authors.lastname: Thorsen
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D001321:Autistic Disorder / Q000209:etiology*; D001724:Birth Weight; D002659:Child Development Disorders, Pervasive / Q000209:etiology*; D003718:Denmark; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007223:Infant; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000009:adverse effects*; D012042:Registries; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors
chemical_list: D022542:Measles-Mumps-Rubella Vaccine