Children at risk for psychotic symptoms if mothers smoke or drink

By Sheilah Downey

Smoking and drinking during pregnancy can lead to development of psychotic symptoms in children, while smoking marijuana was not associated with the problem, according to UK researchers.

In a study of 6,356 participants, 12-year-old children whose mothers smoked during pregnancy, more than 11 percent, or 734, had developed psychotic symptoms such as hallucinations or delusions.

Dr. Stanley Zammit, lead author and psychiatrist at Cardiff University School of Medicine, said that about 19 percent of the children interviewed for the study had mothers who smoked during pregnancy.

"If our results are non-biased and reflect a causal relationship," he said, "we can estimated that about 20 percent of adolescents in this cohort would not have developed psychotic symptoms if their mothers had not smoked. Therefore, maternal smoking may be an important risk factor in the development of psychotic experiences in the population."

The study found also a "dose-response effect," meaning that the risk for psychotic symptoms was highest in children whose mothers smoked the most.

Researchers suggested that tobacco exposure in the womb may affect children's impulses, attention or cognition. They have called for further studies on the affects of in-utero tobacco on the development of the fetus' brains.

According to the study's estimates, 15 and 20 percent of women in the UK smoke during pregnancy.

In the United States, approximately 13 percent of women reported smoking during pregnancy, according to 2004 figures from the Centers for Disease Control.

Babies born to women who smoke have a 30 percent higher chance of being born prematurely, are more likely to have a low birth weight and are 1.4 to 3 times more likely to die from Sudden Infant Death Syndrome, according to the CDC.

In the UK study, psychotic symptoms were also found in children whose mothers drank alcohol during pregnancy, said researchers, but only if more than 21 alcoholic drinks were consumed in one week.

While only a few mothers smoked marijuana during pregnancy, according to  the study, "this was not found to have any significant association with psychotic symptoms."

Researchers from Cardiff, Bristol, Nottingham and Warwick Universities participated in the Avon Longitudinal Study of Parents and Children.

The study was published in the October issue of the British Journal of Psychiatry.