Maternal smoking during pregnancy (MSDP) accounts for some of the aggression exhibited by some children and adolescents, but later experiences may play a larger role in forming adolescent aggressive behavior, according to the results of a study published in Psychological Medicine.
Maternal smoking during pregnancy is associated with a number of adverse outcomes in children, including low birth rate and preterm delivery. Although MSDP has been decreasing in recent years, up to 16.5% of Scandinavian women report smoking during pregnancy.
Margherita Malanchini, PhD, of the Social Genetic and Developmental Psychiatry Centre at King’s College, London, United Kingdom and the Department of Psychology at the University of Texas at Austin, Texas, and colleagues drew on data from 4 prospective twin cohorts: Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study, as part of the EU-ACTION consortium. They analyzed data from 39,708 unrelated individuals and measured aggression at age 9 to 10, 12, 14 to 15, and 16 to 18.
The investigators found that MSDP was associated with aggression in childhood and adolescence. The independent effect of MSDP was 0.4% (r =0.066) across the 4 samples, as determined by meta-analysis. This finding was consistent when the investigators performed the analysis separately by sex. All other perinatal factors combined accounted for 1.1% of the variance in aggression across all ages and samples (r =0.112). Paternal smoking was not associated with aggression, nor did aggressive parenting styles have an effect on aggression.
The study had a number of limitations, including the inability to further explore the genetic associations in this twin cohort and account for familial confounding in the MSDP-aggression association, and the lack of in-depth phenotypic information on parental aggressive behavior.
The investigators concluded that the findings of this study provide evidence for a small direct link between MSDP and aggression across 4 large cohorts in the EU-ACTION consortium.
Malanchini M, Smith-Woolley E, Ayorech Z, et al. Aggressive behaviour in childhood and adolescence: the role of smoking during pregnancy, evidence from four twin cohorts in the EU-ACTION consortium [published online June 11, 2018]. Psychol Med. doi:10.1017/S0033291718001344