title: Is maternal smoking during pregnancy associated with bipolar disorder in offspring?
abstract: BACKGROUND
  Prenatal smoking exposure affects fetal growth and development and is associated with increased risk of various neurodevelopmental disorders. Only one previous study has examined the association between maternal smoking during pregnancy and the risk of bipolar disorder (BPD).
  
  
  METHODS
  In this nested case control study derived from all singleton live births in Finland between January 1st 1987 and December 31st 1998, we identified 724 children diagnosed and/or treated with BPD until 2008 and 1419 matched controls from four nationwide registers. Conditional logistic regression was used to examine the association between maternal smoking during pregnancy and BPD adjusting for potential confounding due to parental psychiatric history, maternal age and education level.
  
  
  RESULTS
  18.5% of offspring were exposed to maternal smoking during pregnancy. In the unadjusted analysis, smoking during pregnancy was associated with a 1.41-fold (95% CI 1.12-1.79, P=0.004) increased risk of BPD. In the final model adjusting for potential covariates, the risk was 1.14-fold (95% CI 0.88-1.49, P=0.323).
  
  
  CONCLUSIONS
  The limitations of this study include: hospital based clinical diagnosis for case ascertainment, inclusion of early onset BPD cases, and lack of information on alcohol or other substance abuse during pregnancy.
  
  
  CONCLUSIONS
  This study demonstrated that, in this sample, an increased risk of BPD among offspring of mothers who smoked during pregnancy is most likely due to confounding by familial background factors. Future studies including information on serological measures of smoking exposure in pregnancy e.g. cotinine are warranted to further clarify this association.
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku, Finland. Electronic address: roschu@utu.fi.
authors.forename: Roshan
authors.initials: R
authors.lastname: Chudal
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, USA; Department of Epidemiology, Columbia University, Mailman School of Public Health, New York, USA.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Brown
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku, Finland; Nordic School of Public Health, Gothenburg, Sweden; National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku, Finland.
authors.forename: Auli
authors.initials: A
authors.lastname: Suominen
authors.affiliation: Department of Child Psychiatry, University of Turku, Turku, Finland; Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York, USA; Department of Child Psychiatry, Turku University Hospital, Turku, Finland; Regional Centre for Child and Youth Mental Health and Child Welfare, University of Tromsø, Tromso, Norway.
authors.forename: Andre
authors.initials: A
authors.lastname: Sourander
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology*; D016022:Case-Control Studies; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D009035:Mothers / Q000706:statistics & numerical data*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D055815:Young Adult
keywords: Bipolar disorder; Prenatal; Smoking during pregnancy