THURSDAY, Oct. 1 (HealthDay News) -- If women need yet another reason to avoid smoking during pregnancy, researchers now say that tobacco use by expectant mothers may raise the risk that their children will develop psychotic symptoms.

The new research, published in the October issue of the British Journal of Psychiatry, doesn't prove that smoking during pregnancy causes the psychotic behavior, but it does suggest a link.

In the study of 6,356 children in the United Kingdom, more than 11 percent of the 12-year-olds appeared to have definite or suspected symptoms of psychosis.

The researchers found that the children whose mothers smoked during pregnancy were more likely to have the symptoms, and the risk rose in those whose mothers smoked the most while pregnant.

Maternal alcohol use was also linked to more psychotic symptoms in children, but only among those whose mothers drank more than 21 units of alcohol a week during the early weeks of pregnancy (with one unit being roughly equivalent to a half-pint of beer or a glass of wine). The researchers couldn't find any link between maternal marijuana use and psychotic symptoms in children among the few women who reported using the drug during pregnancy.

The study authors suspect that tobacco exposure in the womb may indirectly affect the development and function of a child's brain, impacting impulsivity, attention or cognition.

"If our results are non-biased and reflect a causal relationship, we can estimate that about 20 percent of adolescents in this cohort would not have developed psychotic symptoms if their mothers had not smoked," study author Dr. Stanley Zammit, a psychiatrist at Cardiff University's School of Medicine in Wales, said in a news release from the journal. "Therefore, maternal smoking may be an important risk factor in the development of psychotic experiences in the population."

More information

Learn tips for a healthy pregnancy from the U.S. Centers for Disease Control and Prevention.

-- Randy Dotinga

SOURCE: British Journal of Psychiatry, news release, Oct. 1, 2009

Last Updated: Oct. 01, 2009

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