Margherita Malanchini 1 , 2 , Emily Smith-Woolley 1 , Ziada Ayorech 1 , Kaili Rimfeld 1 , Eva Krapohl 1 , Eero Vuoksimaa 3 , Tellervo Korhonen 3 , Meike Bartels 4 , Toos C.E.M. van Beijsterveldt 4 , Richard J. Rose 5 , Sebastian Lundström 6 , Henrik Anckarsäter 6 , Jaakko Kaprio 3 , 7 , Paul Lichtenstein 8 , Dorret I. Boomsma 4 , Robert Plomin 1
11 June 2018
Maternal smoking during pregnancy (MSDP) has been linked to offspring's externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a comprehensive investigation of the association between MSDP and a single harmonized component of externalizing: aggressive behaviour, measured throughout childhood and adolescence.
Data came from four prospective twin cohorts – Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study – who collaborate in the EU-ACTION consortium. Data from 30 708 unrelated individuals were analysed. Based on item level data, a harmonized measure of aggression was created at ages 9–10; 12; 14–15 and 16–18.
MSDP predicted aggression in childhood and adolescence. A meta-analysis across the four samples found the independent effect of MSDP to be 0.4% ( r = 0.066), this remained consistent when analyses were performed separately by sex. All other perinatal factors combined explained 1.1% of the variance in aggression across all ages and samples ( r = 0.112). Paternal smoking and aggressive parenting strategies did not account for the MSDP-aggression association, consistent with the hypothesis of a small direct link between MSDP and aggression.