Despite wide awareness that smoking is bad for both mother and developing fetus, in 2007, an estimated 16.4 percent of pregnant American women were current tobacco smokers (SAMHSA, 2008
). Although pregnant women overall had lower smoking rates than nonpregnant women, pregnant 15- to 17-year-olds had higher smoking rates than their nonpregnant age mates.
Smoking increases a woman’s risk of ectopic pregnancy and placenta previa, both of which increase the odds of maternal mortality. Women who smoke during pregnancy are somewhat less likely to develop preeclampsia than those who do not smoke; however, among pregnant women who develop preeclampsia, smoking seems to increase mortality (Cnattingius, 2004
Tobacco use has also been linked to low birth weight and pregnancy complications, including prematurity, placental abruption, and intrauterine death. Low birth weight suggests that the fetus has not obtained important nutrients and oxygen, which are important for optimal brain growth and neuronal development. Some evidence indicates that maternal tobacco use during pregnancy doubles the likelihood of sudden infant death syndrome (Salihu and Wilson, 2007
Prenatal Drug Exposure: Potential Effects on Birth and Pregnancy Outcomes
Neonates who were exposed to tobacco prenatally are more excitable, have greater muscle tension, require more handling to be calmed, and show more signs of CNS stress (e.g., abnormal sucking, excessive gas, gaze aversion) than unexposed infants (Law et al., 2003
). Dose-response relationships have been established between maternal tobacco use, as measured by levels of salivary cotinine (the active metabolite of nicotine) or self-report, and signs of physiological stress.
Infant CNS functional abnormalities related to pre-natal tobacco exposure include deficits in self-regulation (the infant’s ability to soothe or quiet itself) (). At 2 to 4 weeks and at 7 months of age, prenatally tobacco-exposed infants exhibited, compared with unexposed infants, more negative affect and manifestations of sadness, distress in response to limitations, decreased soothability, and fear during a test used to assess emotional self-regulation (Schuetze and Eiden, 2007
; Schuetze, Eiden, and Coles, 2007
). Low birth weight and reduced head growth may underlie these disturbances.
Prenatal Drug Exposure: Potential Effects on Central Nervous System Development, Cognitive Function, and Behavior*
Prenatal tobacco exposure has been consistently associated with lower IQ throughout childhood (Fried, 2002
; Herrmann, King, and Weitzman, 2008
). In one study, children of women who smoked more than 16 cigarettes a day while pregnant had a mean IQ in the average range, but 8 points lower than those of unexposed children (Fried, Watkinson, and Gray, 2003
). Children prenatally exposed to tobacco are also at increased risk for attention problems during the early elementary school years (Cornelius et al., 2007
; Langley et al., 2005
; Linnet et al., 2003
In 2007, an estimated 16.4 percent of pregnant American women were current tobacco smokers.
Conduct disorder can be an adverse outcome of prenatal tobacco exposure. In one study, adolescent children of mothers whose blood cotinine levels during pregnancy had been in the top 20 percent of those tested were twice as likely as the 20 percent of children with the least exposure to develop a conduct disorder (Braun et al., 2008
). Postnatal exposure to secondhand smoke may also contribute substantially to diagnoses of conduct disorder in U.S. children (Braun et al., 2008
). Recent data suggest that prenatal tobacco exposure may promote later conduct disorders by inhibiting the brain enzyme monoamine oxidase (MAO) during fetal development (Baler et al., 2008
). MAO participates in the regulation of the levels of monoaminergic neurotransmitters that are critical for fetal forebrain development.
Prenatal tobacco exposure has also been implicated in depression and anxiety in early childhood through late adolescence (Robinson et al., 2008
). However, these internalizing symptoms have not received as much attention as conduct disorder, perhaps because they are less disruptive to families and classrooms.
Prenatal tobacco exposure appears to increase the likelihood of tobacco use in childhood and early adolescence. In one study, the risk differential of exposed and unexposed children at age 10 was more than five-fold after controlling for environmental factors, other prenatal exposures, current maternal smoking, and child and maternal psychological covariates (Cornelius et al., 2005
). However, when the children in this study were 14, prenatal tobacco exposure was no longer a significant predictor of their tobacco use when factors such as peer smoking were taken into account.
A magnetic resonance imaging (MRI) study of children aged 10 to 14 found reductions in cortical gray matter and parenchyma volumes, as well as head circumference, in those whose mothers had smoked while pregnant (Rivkin et al., 2008
). Some researchers have suggested that prenatal tobacco exposure accelerates puberty among males (Fried, James, and Watkinson, 2001
Behavioral interventions are recommended as the first treatment options to help pregnant women stop smoking (Oncken and Kranzler, 2009
; Slotkin, 1998
). Several studies have demonstrated that contingency management (CM), a strategy that dispenses cash or other tangible prizes as incentives for achieving treatment goals, helps pregnant smokers maintain abstinence (Donatelle et al., 2000
; Heil, Scott, and Higgins, 2009
; Higgins et al., 2004
). CM may be more effective with low-income pregnant smokers (Donatelle et al., 2004
), whose quit rates with CM have ranged from 19 to 40 percent, compared with 6.6 to 20.5 percent with other behavioral interventions. On its own, cognitive-behavioral therapy (CBT) yields only modest reductions in smoking-cessation rates among pregnant women. Combined treatment with CBT and nicotine replacement therapy (NRT) is more effective than CBT alone for pregnant moderate to heavy smokers (Osadchy, Kazmin, and Koren, 2009
Behavioral interventions are recommended as the first treatment options to help pregnant women stop smoking.
Although NRT is widely used and effective in the general population, there are concerns regarding its effectiveness for pregnant smokers and safety for the fetus. At issue is whether the risks for both mother and child outweigh the harmful effects of cigarette smoking on the fetus. Some researchers endorse the use of NRT under a physician’s close supervision in combination with behavioral interventions for moderate to heavy smokers (Osadchy, Kazmin, and Koren, 2009
). For heavy smokers, the benefits of NRT likely outweigh the risks of smoking during pregnancy because NRT (1) usually delivers a dose of nicotine less than or the same as what the person gets from smoking, (2) may eliminate fetal exposure to other toxins in cigarette smoke, and (3) may reduce the overall dose and duration of nicotine exposure (Oncken and Kranzler, 2003
). When used, NRT therapy should begin as early in the pregnancy as possible, because a fetus may be especially sensitive to the adverse effects of nicotine exposure after the first trimester (Slotkin, 1998
). The safety and efficacy of bupropion, another medication that is effective for smokers in the general population, has not been established for pregnant smokers (Oncken and Kranzler, 2003
Abstinence from smoking during the first 2 weeks of a quit attempt is critical to long-term success (Higgins et al., 2006
). It is therefore important to closely monitor early abstinence and adjust treatment as needed. Clinicians should continue to encourage women to quit even if they initially fail, because quitting at any time before childbirth reduces the risk of complications for both the mother and child.