mothers smoking during pregnancy. Besides a gene-mediated effect, maternal smoking during pregnancy might increase the risk of smoking in the offspring via intrauterine exposure to nicotine(58). In our data, the effect of maternal smoking in pregnancy became non-significant after adjusting for maternal smoking before pregnancy. This indicates that the observed association between maternal and offspring smoking behaviors is not likely to reflect a prenatal exposure, but more likely a postnatal mechanism [i.e. mothers smoking during pregnancy are probably more likely to smoke also after delivery exposing their offspring to a tobacco enriched environment(58)].
