title: The risk of childhood autism among second-generation migrants in Finland: a case-control study.
abstract: BACKGROUND
  Studying second-generation immigrants can help in identifying genetic or environmental risk factors for childhood autism. Most previous studies have focused on maternal region of birth and showed inconsistent results. No previous study has been conducted in Finland.
  
  
  METHODS
  The study was a nested case-control study based on a national birth cohort. Children born in 1987-2005 and diagnosed with childhood autism by the year 2007 were identified from the Finnish Hospital Discharge Register. Controls were selected from the Finnish Medical Birth Register. Information on maternal and paternal country of birth and mother tongue was collected from the Finnish Central Population Register. There were 1132 cases and 4515 matched controls. The statistical test used was conditional logistic regression analysis.
  
  
  RESULTS
  Compared with children with two Finnish parents, the risk of childhood autism was increased for those whose parents are both immigrants (adjusted odds ratio [aOR] 1.8, 95% confidence interval [CI] 1.2-2.7) and for those with only an immigrant mother (aOR 1.8, 95% CI 1.2-2.7), but not for those with only an immigrant father. The risk was increased for those with a mother born in the former Soviet Union or Yugoslavia and for those with a mother or a father born in Asia. Specific parental countries of birth associated with an increased risk were the former Soviet Union, the former Yugoslavia and Vietnam.
  
  
  CONCLUSIONS
  In Finland, children who are born to immigrant mothers with or without an immigrant partner, have an increased risk of childhood autism. The risk varies with immigrant parents' region of birth. The findings may help in identifying possible risk factors, which can be examined in future studies.
authors.forename: Venla
authors.initials: V
authors.lastname: Lehti
authors.forename: Susanna
authors.initials: S
authors.lastname: Hinkka-Yli-Salomäki
authors.forename: Keely
authors.initials: K
authors.lastname: Cheslack-Postava
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Alan S
authors.initials: AS
authors.lastname: Brown
authors.affiliation: Department of Child Psychiatry, University of Turku, Lemminkäisenkatu 3 / Teutori, Turku 20014, Finland. andre.sourander@utu.fi.
authors.forename: Andre
authors.initials: A
authors.lastname: Sourander
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D054242:Emigrants and Immigrants; D004781:Environmental Exposure; D005220:Fathers; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007802:Language; D008297:Male; D009035:Mothers; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012042:Registries; D012306:Risk; D018401:Sample Size; D014586:USSR / Q000208:ethnology; D014744:Vietnam / Q000208:ethnology; D055815:Young Adult; D015022:Yugoslavia / Q000208:ethnology