Smoking During and After Pregnancy

Effects on Activity, Attention, and Impulsivity
by National Institute of Health

(Page 3 of 4)

Researchers have also reported associations between prenatal tobacco exposure and increased activity, inattention, and impulsivity. Streissguth and colleagues reported significant relationships between prenatal tobacco exposure and errors of omission and commission, reflective of inattention and impulsivity, respectively, in 4-year-olds. Kristjansson and colleagues found that prenatal tobacco exposure predicted impulsivity and increased overall activity among 4- to 7-year-olds after controlling for prenatal exposure to other drugs and postnatal exposure to second-hand smoke. In addition, Fried and colleagues reported a significant relationship between prenatal tobacco exposure and impulsivity among 6-year-olds in the same cohort.

Milberger and colleagues found a positive relationship between maternal smoking during pregnancy and an increased risk of attention deficit hyperactivity disorder in exposed children between the ages of 6 and 17, although the study did not control for current maternal smoking or prenatal exposure to other substances. In the MHPCD study of adult mothers, prenatal tobacco exposure significantly predicted increased errors of commission on the Continuous Performance Test among 6-year-olds. However, the mothers' current tobacco use correlated so highly with the prenatal exposure levels that these exposures could not be separated. Eskenazi and Trupin did not find a relationship between prenatal tobacco use and activity.

When the children of the adult mothers in the MHPCD study were assessed at age 10, prenatal tobacco exposure predicted deficits on neuropsychological tests that measured planning ability and fine motor coordination. These deficits persisted after controlling for maternal current smoking, prenatal exposure to other substances, and covariates of prenatal and current substance use.

Behavioral and Psychological Effects

Behavioral and psychological problems have also been linked to prenatal tobacco exposure. Orlebeke and colleagues reported a significant effect of prenatal tobacco exposure on externalizing behaviors, including oppositional, aggressive, and overactive behaviors in 3-year-olds. This study did not control for other prenatal substance exposures or the mothers' current smoking habits. Weitzman and colleagues found that women who smoked both during and after pregnancy rated their children as having more behavior problems, but the researchers found no effects on children who were only exposed during pregnancy. Brook and colleagues found that mothers who smoked during pregnancy were significantly more likely to have toddlers who displayed negativity than did mothers who only smoked after delivery. This relationship was maintained after controlling for a number of psychosocial risk factors, including the mother's distress, socioeconomic status, and perinatal risk factors. In the adult cohort of the MHPCD project, 3-year-olds who were exposed prenatally to tobacco were significantly more likely to display oppositional behavior, immaturity, and aggressive behavior, according to the mothers' reports. These relationships persisted after controlling for socioeconomic status, current home environment, maternal psychological status, current maternal tobacco use, and other prenatal substance exposures.

The behavior problems observed in toddlers prenatally exposed to tobacco persist through the adolescent and adult years. Fergusson and colleagues followed a birth cohort through age 12 and reported that prenatal tobacco exposure was significantly related to childhood behavior problems, whereas current maternal smoking was not. At ages 16 to 18, children in that cohort who were exposed to prenatal smoking had higher rates of conduct disorder, substance use, and depression than did nonexposed children. Wakschlag and colleagues also reported a significant relationship between prenatal tobacco exposure and conduct disorder in a clinical sample; however, this study did not control for current exposure. In addition, maternal smoking during pregnancy predicted persistent criminal outcomes in adult male offspring in a Danish prospective study. That study controlled for a number of demographic variables, but it did not control for prenatal alcohol and illicit drug exposure or for environmental tobacco exposure. In another prospective study in Finland, maternal smoking during pregnancy was significantly associated with an increase in violent offenses among the adult male offspring.

A few studies have evaluated the relationships between prenatal substance exposure and subsequent substance use in the offspring. Animal researchers have noted that changes resulting from prenatal nicotine exposure might affect susceptibility to later tobacco use. In a retrospective study of humans, Kandel and colleagues reported a fourfold increased risk of tobacco use among female offspring who were exposed to tobacco prenatally. In a later report, Griesler and colleagues showed that maternal smoking during pregnancy was significantly associated with higher levels of child behavior problems and that these behavior problems increased the likelihood of smoking among daughters between the ages of 9 and 17. The association between prenatal tobacco exposure and early tobacco experimentation was also found in the MHPCD prospective study of adult women and their offspring. In this study, 10-year-old children exposed to tobacco at the level of at least one half pack per day during gestation had a 5.5-fold increased risk for early tobacco experimentation, controlling for prenatal exposure to other substances and their mothers' current smoking habits.

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