title: Prenatal smoking exposure and offspring stress coping in late adolescence: no causal link.
abstract: BACKGROUND
  In utero exposure to tobacco smoking has been suggested to cause persistent alterations in cognitive functioning. We examined if mothers' smoking during pregnancy (SDP) is associated with long-term impairment in offspring stress coping and the causal mechanism behind a possible link.
  
  
  METHODS
  We used a large cohort (n = 187,106) of young males in Sweden (mean age = 18.2 years), who underwent a semi-structured psychological assessment in 1997-2006, including an evaluation of stress coping ability, as part of the compulsory military conscript examination. We compared differentially exposed siblings within nuclear families and cousins in extended families and used multilevel structural equation models to disentangle genetic from environmental contributions to the association between SDP and stress coping.
  
  
  RESULTS
  SDP and offspring stress coping was moderately strongly associated when comparing unrelated individuals [regression coefficient (b) = -0.38 on a nine-point scale; 95% confidence interval (CI) -0.40 to -0.36, P < 0.0001]. In contrast, it disappeared when siblings were compared (b = 0.11; 95% CI -0.01 to 0.23, P = 0.071). This familial confounding was entirely due to genetic influences.
  
  
  CONCLUSIONS
  SDP is an established risk factor for pregnancy- and birth-related complications. However, we found no long-term effect of SDP on offspring stress coping. Rather, the observed association was due to familial confounding of genetic origin; women prone to SDP also transmit genes to their children that are associated with poorer coping with stress.
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. ralf.kuja-halkola@ki.se
authors: Ralf
authors: R
authors: Kuja-Halkola
authors: Brian M
authors: BM
authors: D'Onofrio
authors: Anastasia N
authors: AN
authors: Iliadou
authors: Niklas
authors: N
authors: Långström
authors: Paul
authors: P
authors: Lichtenstein
mesh_terms: D000223:Adaptation, Psychological; D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D000328:Adult; D015984:Causality; D015331:Cohort Studies; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008423:Maternal Age; D008425:Maternal Behavior; D008889:Military Personnel; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000209:etiology* / Q000523:psychology*; D012042:Registries; D012044:Regression Analysis; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013315:Stress, Psychological / Q000453:epidemiology / Q000209:etiology*; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult