Moreover, preliminary efforts to study the fetal programming hypothesis, as described above, from a phenotypic standpoint (i.e., in the absence of epigenetic data), using low birth weight as a proxy for poor gestational environment, suggest that this mechanism does not wholly explain potential prenatal smoke exposure influences on later psychological functioning (Kuja-Halkola, et al., 2010). Kuja-Halkola and colleagues also suggest that possible effects of low birth weight on later offspring behavior may also be due to familial confounding (Kuja-Halkola, et al., 2010). Thus, further biological characterization, such as specific genetic influences as well as epigenetic modification resulting from pre-pregnancy smoking that has influence irrespective of the decision to smoke during pregnancy may further highlight influences beyond maternal cigarette smoking during pregnancy and add clarity to this complicated story.
