Examples of prenatal smoking exposure research in childhood are many (see Knopik et al., 2009 for a review), perhaps because of more sensitive assessments for this age group, relative to infants. For instance, Olds et al. conducted a study investigating associations between maternal cigarette smoking during pregnancy and offspring intelligence at age 4, finding that children whose mothers smoked 10 or more cigarettes per day during their pregnancy exhibited intellectual impairment relative to children whose mothers did not smoke cigarettes during pregnancy (Olds, Henderson, & Tatelbaum, 1994). Huijbregts et al found associations between maternal cigarette smoking during pregnancy and physical aggression during early childhood (Huijbregts, Seguin, Zoccolillo, Boivin, & Tremblay, 2007, 2008). This is consistent with multiple studies suggesting an association of prenatal smoke exposure and increased externalizing disorders, such as conduct disorder and attention deficit hyperactivity disorder (Abbott & Winzer-Serhan, 2012; Cornelius & Day, 2009; Knopik, 2009). Cognitive function has also been shown to be negatively affected by maternal smoking during pregnancy, with deficits in sustained attention (Fried, O’Connell, & Watkinson, 1992; Fried, Watkinson, & Gray, 1992), response inhibition,
