Familial Confounding of the Association Between Maternal Smoking During Pregnancy and Offspring Criminality

Abstract

Context The association between maternal smoking during pregnancy (SDP) and offspring disruptive behaviors has been well documented, but it is unclear whether exposure to SDP or the effects of factors correlated with SDP account for the increased risk. Objective To test whether the association between SDP and offspring criminal convictions was consistent with a causal connection or due to familial background factors by controlling for measured covariates and using a quasi-experimental approach. Design We used a population-based study of children born in Sweden from 1983–1989 (N=609,372) to examine the association between SDP and offspring criminal convictions, while controlling for measured traits of both parents. We also compared siblings differentially exposed to SDP (N=50,339) to account for unmeasured familial factors that could account for the association. Setting Population-based study of all children born in Sweden from 1983–1989 with information on maternal SDP and offspring criminal convictions, based on national registries collected by the Swedish government. Main Outcome Measures Violent and nonviolent convictions, based on the Swedish National Crime Register, a register with detailed information on all convictions in the country. Results Moderate (HR=2.47, CI=2.34–2.60) and high levels (HR=3.43, CI=3.25–3.63) of maternal SDP was associated with an increased risk for offspring violent convictions, even when controlling for maternal and paternal traits. There was no association between SDP and violent convictions, however, when comparing differentially exposed siblings (HRmoderate=1.02, CI=0.79–1.30; HRhigh=1.03, CI=0.78–1.37). SDP also was associated with nonviolent convictions in the entire population (HRmoderate=1.62, CI=1.58–1.66; HRhigh=1.87, CI=1.82–1.92) and when controlling for covariates. But, there was no association when comparing siblings who were differentially exposed (HRmoderate=0.89, CI=0.78–1.01; HRhigh=0.89, CI=0.78–1.02). Conclusions The results suggest that familial background factors account for the association between maternal SDP and criminal convictions, not the specific exposure to SDP.

Prenatal Smoking Exposure and the Risk of Behavioral Problems and Substance Use in Adolescence: the TRAILS Study

“…A Dutch birth cohort study appeared to account for all relevant confounding factors, but did not use a standardized and validated instrument to assess externalizing behavioral problems [34] . In line with the results of the present study, a population-based study in Sweden, comparing siblings differentially exposed to prenatal smoking, demonstrated that the association between maternal smoking in pregnancy and offspring criminality was fully accounted for by familial background factors [38] . Boutwell and Beaver [39] , using a propensity scorematching analysis, concluded that the relationship between smoking during pregnancy and externalizing behavioral problems was spurious.…”

“…the strength of all relationships decreased substantially when potentially confounding factors were included in the model. These findings are in line with a number of recent quasi-experimental studies, comparing siblings differentially exposed to MSP, concluding that familial background factors and not the specific exposure to MSP account for the associations between MSP and offspring behavioral outcomes [30][31][32][33] . The fact that a substantial number of studies [3,[34][35][36][37] , including a recent, welldesigned and powered birth cohort study in Finland [5] , concluded that MSP increases the risk for offspring behavioral problems, is most likely explained by the fact that these studies did not adequately address the issue of confounding.…”

Perinatal Risk Factors in Offenders with Severe Personality Disorder: A Population-based Investigation

“…The associations found in this study are not necessarily causal, and may be linked by other common factors independently related to obstetric factors and personality disorders including genetic factors Thapar & Rutter 2009;D'Onofrio et al, 2010). One possibility is that the mothers of the cases may also have had personality disorder (Torgersen et al, 2008), and thus increase the risk of birth complications by abuse of substances or through suboptimal adherence to prenatal health care.…”

“…Earlier findings of clear associations between obstetric complications and prenatal exposure to maternal smoking with violent crime in adulthood (Raine et al, 1997;Brennan et al, 2002;Pratt et al, 2006) have been subsequently challenged. In particular, the association with maternal smoking appears to be confounded by familial factors (D'Onofrio et al, 2010), and the relationship of criminality with obstetric complications has not been shown to be independent of adverse parenting (Hodgins et al, 2001) or adverse family environments (Arseneault et al, 2002). However, associations with violent outcomes in mentally ill populations may be independent of interactions with early environmental factors Hodgins et al, 2002).…”

Widespread covariation of early environmental exposures and trait-associated polygenic variation

“…This includes both parenting characteristics and broad socioeconomic variables; all are partially heritable (23)(24)(25)(26)(27)(28). In the past decade, quantitative genetic research of this type has been extended to explore genetic and environmental contributions to correlations between environmental factors and children's outcomes (29)(30)(31)(32). Some new designs such as the children-of-twins designs make it possible to tease apart different types of genotype-environment correlation and identify environmental influences free of genetic confounds (33)(34)(35)(36)(37).…”