Previous epidemiological, animal, and human cognitive neuroscience research suggests that maternal smoking during pregnancy causes increased risk of offspring substance use/problems.
To determine the extent to which the association between SDP and offspring substance use/problems depends on confounded familial background factors by using a quasi-experimental design.
We used two separate samples, from the United States and from Sweden, respectively. The analyses prospectively predicted multiple indices of substance use and problems while controlling for statistical covariates and comparing differentially exposed siblings to minimize confounding.
Sample 1: Offspring of a representative sample of women in the United States. Sample 2: The total Swedish population born over 13 years.
Patients or Other Participants
Sample 1: Adolescent offspring of the women in the National Longitudinal Survey of Youth 1979 (n=6,094). Sample 2: All offspring born in Sweden from 1983 through 1995 (n=1,187,360).
Main Outcome Measures
Sample 1: Self-reported adolescent alcohol, cigarette, and marijuana use, and early onset (before age 14 years) of each substance. Sample 2: Substance-related convictions and hospitalizations for an alcohol- or drug-related problem.
The same pattern emerged for each index of substance use/problems across the two samples. At the population level maternal smoking during pregnancy predicted every measure of offspring substance use/problems in both samples, ranging from adolescent alcohol use (HRmoderate=1.32, CI=1.22–1.43; HRhigh=1.33, CI=1.17=1.53) to a narcotic convictions (HRmoderate=2.23, CI=2.14–2.31; HRhigh=2.97, CI=2.86–3.09). When comparing differentially exposed siblings to minimize genetic and environmental confounds, however, the association between SDP and each measure of substance use/problems was minimal and not statistically significant.
The association between maternal smoking during pregnancy and offspring substance use/problems was likely due to familial background factors, not a causal influence, because siblings had similar rates of substance use and problems regardless of their specific exposure to smoking during pregnancy.