As suggested by this review, there is a growing literature on maternal cigarette smoking during pregnancy and epigenetic phenomena, such as DNA methylation and miRNA expression. How do we align these recent advances with the smoking during pregnancy literature at large, particularly the reported associations between smoking during pregnancy and later child/adolescent behavior? There is a large literature suggesting undesirable outcomes in children exposed to maternal smoking during pregnancy. This evidence (in human models), until recently, has been limited by the frequent inability to separate prenatal exposure effects from other confounding environmental and genetic factors. The vast majority of studies have provided very limited control for the fact that prenatal exposures may be correlated with parental behaviors that could act as more proximal risk factors that are, in turn, transmitted to their offspring (Knopik, 2009). In other words, mothers who smoke during their pregnancies share other risk factors with their children and it may be these other risk factors that are associated with the observed adverse outcomes rather than only maternal cigarette smoking during pregnancy per se (Kuja-Halkola, D’Onofrio, Iliadou,
