Important work still needs to be done to determine the mechanisms affected by such exposures which may lead to neurodevelopmental and neurobehavioral outcomes. DNA methylation patterns in both candidate gene promoters as well as on more genomewide levels should be assessed using both animal models of maternal cigarette smoking during pregnancy as well as human cohorts. Additional studies which may be of special note might include an investigation of associations of maternal cigarette smoking during pregnancy on DNA methylation of the promoter of the glucocorticoid receptor (GR). This receptor is known to be a mediator of glucocorticoid signaling (a major component of the stress-response system that is closely linked to depression and anxiety psychopathology), and previously shown to be regulated, in part, by DNA methylation (Filiberto et al., 2011; Herbeck, Gulevich, Amelkina, Plyusnina, & Oskina, 2010; Ke et al., 2010; Oberlander et al., 2008; Weaver et al., 2004; Weaver et al., 2001). While previous studies have controlled for maternal cigarette smoking during pregnancy and did not find significant associations between maternal cigarette smoking during pregnancy and aberrant methylation at the
