Smoking during pregnancy and offspring externalizing problems: an exploration of genetic and environmental confounds

Abstract

Previous studies have documented that smoking during pregnancy (SDP) is associated with offspring externalizing problems, even when measured covariates were used to control for possible confounds. However, the association may be because of nonmeasured environmental and genetic factors that increase risk for offspring externalizing problems. The current project used the National Longitudinal Survey of Youth and their children, ages 4-10 years, to explore the relations between SDP and offspring conduct problems (CPs), oppositional defiant problems (ODPs), and attention-deficit/hyperactivity problems (ADHPs) using methodological and statistical controls for confounds. When offspring were compared to their own siblings who differed in their exposure to prenatal nicotine, there was no effect of SDP on offspring CP and ODP. This suggests that SDP does not have a causal effect on offspring CP and ODP. There was a small association between SDP and ADHP, consistent with a causal effect of SDP, but the magnitude of the association was greatly reduced by methodological and statistical controls. Genetically informed analyses suggest that unmeasured environmental variables influencing both SDP and offspring externalizing behaviors account for the previously observed associations. That is, the current analyses imply that important unidentified environmental factors account for the association between SDP and offspring externalizing problems, not teratogenic effects of SDP.

Figure 1

Associations between SDP and offspring externalizing problems using different methodological and statistical controls. Note. There was no interaction between SDP and offspring sex for ODP and ADHP.

Figure 2

Structural equation model for the offspring of siblings and twins. Note. Smoking during pregnancy (SDP) and offspring externalizing (EXT). Unbroken lines represent the maternal and NLSY Household-level of the analysis. The hyphenated lines represent the offspring-level (within-maternal). See Harden et al. (in press) for a comparison to the specific Children of Twins model.