تاثیرات سیگار کشیدن مادر در دوران بارداری (MSDP) بر نتایج فرزندان

ABSTRACT The effects of maternal smoking during pregnancy on offspring outcomes

In 2006, 17% of women giving birth reported cigarette smoking during pregnancy during their last trimester (Centers for Disease Control (CDC), 2004; PRAMS, 2007). While persistent cigarette smoking itself is one of the leading contributors to preventable death (Centers for Disease Control (CDC), 2002), maternal smoking during pregnancy (MSDP) has in and of itself been implicated as a potential risk factor associated with multiple offspring outcomes such as low birth weight, conduct disorder (CD), attention deficit hyperactivity disorder (ADHD), offspring smoking and cognitive dysfunction (Knopik, 2009).

Low birth weight and other birth outcomes

There is considerable evidence supporting the hypothesis that offspring of mothers who smoke during their pregnancies have impaired fetal growth, preterm birth and lower birth weight infants (Conter et al., 1995; D’Onofrio et al., 2003; Knopik et al., 2005; Bada et al., 2005; Salihu et al., 2005; Kyrklund-Blomberg et al., 2005; Stroud et al., 2009; McCowan et al., 2009; Thiriez et al., 2009), which, in turn, are correlated with a host of neuropsychological developmental delays. Of these, the association between MSDP and low birth weight appears to account for many of the associated outcomes, replicating consistently in prospective and retrospective studies.

Cognitive dysfunction and impaired learning

Some studies report impaired learning in those prenatally exposed to cigarette smoke, although results are equivocal (Bauman et al., 1991; Eskenazi and Trupin, 1995; Cornelius et al., 2001; Batstra et al., 2003; Mortensen et al., 2005; Lambe et al., 2006). Using an array of laboratory tasks, Cornelius et al. (2001) found support for an association between MSDP and deficits in multiple aspects of learning and memory. In another study, MSDP was associated, via familial factors, with poor school performance (Lambe et al., 2006).

Externalizing behaviors

While the mechanism underlying their association is still under investigation, several studies report higher rates of externalizing behaviors, including attention deficit hyperactivity disorder (ADHD), conduct disorder (CD) as well as higher impulsivity and other problem behaviors in the offspring of mothers who smoked during their pregnancy (Milberger et al., 1996; Fergusson et al., 1998; Wakschlag et al., 2002, 2006; Batstra et al., 2003; Maughan et al., 2004; Knopik et al., 2005, 2009; Cornelius et al., 2007; D’Onofrio et al., 2008). Two recent studies have investigated the familial links between MSDP and externalizing disorders (Knopik et al., 2006; D’Onofrio et al., 2008) — broadly, these studies suggest that familial factors partially contribute to the association between MSDP and externalizing behavior, although the mechanisms are unclear. Multiple studies also report the association between MSDP and externalizing behaviors to be explained by maternal problem behaviors (Orlebeke et al., 1999; Silberg et al., 2003; Maughan et al., 2004).

Offspring smoking

There is growing evidence that prenatal exposure to cigarette smoking increases the likelihood of cigarette smoking in the offspring (Cornelius et al., 2000, 2005). Given the high correlation between maternal nicotine dependence and MSDP (Agrawal et al., 2008; O’Callaghan et al., 2009), these youths represent a particularly vulnerable group of individuals with both increased genetic (inherited often from both parents who are smokers) and environmental risk (attributable to MSDP and potentially, via exposure to parents who smoke) risk.

In this study, using data on 1,342 unique pregnancies, with offspring aged 12–32, their fathers and mothers, we investigate the association between MSDP and offspring outcomes of low birthweight, pre-term birth, remediation, low scholastic achievement, ADHD, CD problems and regular smoking in the offspring. We highlight the importance of controlling for the influence of parental behaviors in studies of MSDP and offspring outcomes and, as a secondary analysis, also test for potential genetic and environmental links that may contribute to the relationship between MSDP and offspring outcomes.