Vol. 4, No. 4, 1998 Page 3

Mothers' smoking linked to children's
IQ, behavior problems

Two recent studies add to evidence linking prenatal tobacco exposure to low IQ or childhood behavior problems, both risk factors for later criminality.

David Fergusson et al. reviewed data from 1,022 children followed for 18 years in the Christchurch Health and Development Study. The researchers controlled for a variety of prenatal, environmental, and socioeconomic factors.

Fergusson and colleagues found a significant correlation between maternal smoking and the occurrence of conduct disorders in children between the ages of 16 and 18. "Children whose mothers smoked one pack of cigarettes or more per day during their pregnancy," the researchers report, "had mean rates of conduct disorder symptoms that were twice as high as those found among children born to mothers who did not smoke during their pregnancy." The link was stronger for male teens than for females.

In separate research, Peter Fried and colleagues studied 131 children between the ages of 9 and 12, all whom had been exposed before birth to tobacco and/or marijuana. The researchers found a dose-dependent association between prenatal cigarette exposure and lower overall intelligence scores. In particular, children with greater exposure to tobacco had lower scores on verbal IQ measures.

Prenatal exposure to marijuana did not affect overall intelligence or verbal intelligence scores, the researchers say. Rather, marijuana exposure before birth appeared to impair executive function skills. These skills, believed to be mediated by the frontal lobes of the brain, include impulse control and judgment.

In earlier research (See Crime Times Vol. 3, No. 3, 1997, p. 7), (see related article, Crime Times, 1997, Vol. 3, No. 3, Page 7). Jacob Orlebeke and colleagues studied 1,377 three-year-old twin pairs, and found a significant effect of maternal smoking on oppositional, aggressive, and overactive behavior. Aggression was the behavior most strongly linked to maternal smoking.


"Maternal smoking during pregnancy and psychiatric adjustment in late adolescence," David Fergusson, Lianne Woodward, and L. John Horwood, Archives of General Psychiatry, Vol. 55, Aug. 1998, pp. 721-727. Address: David M. Fergusson, Dept. Psychological Medicine, Christchurch School of Medicine, P.O. Box 4345, Christchurch, New Zealand.


"Differential effects on cognitive functioning in 9- to 12-year-olds prenatally exposed to cigarettes and marihuana," Peter Fried, Barbara Watkinson, and Robert Gray, Neurotoxicology and Teratology, Vol. 20, No. 3, 1998, pp. 293-306. Address: Peter A. Fried, Psychology Dept., Carleton University, Ottawa, Ontario, Canada K1S 5B6.

Related Article: [2000, Vol. 6]

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