Mothers-to-be who smoke are at a higher risk of delivering physically aggressive children, a new study shows, adding to the expansive list of harmful effects of lighting up.
What's more, the study found pregnant women with a history of antisocial behaviour - from run-ins with the law to illegal drug use - are almost 70 per cent more likely to have a violent child if they smoke 10 cigarettes a day, compared with 16 per cent for those who are non-smokers or who smoke fewer than 10 cigarettes.
Smoking while pregnant has been linked to premature births, low birth weight, sudden infant death syndrome, birth defects and chronic respiratory illnesses.
University of Montreal psychiatry professor Jean Séguin, co-author of the study that appears in the journal Development and Psychopathology, said the paper is proof that mothers who light up can predispose their offspring to yet another risk.
"The fact that we ... see it [violent behaviour] in very young children is a sign that cigarette smoking is not a good thing. During pregnancy, it's not a good thing," Dr. Séguin said yesterday. "It affects the nervous system of the children in many ways, and this is one of them. It makes the kid harder to manage."
The research was part of a wider study looking at the behaviour of more than 1,700 Quebec children between the ages of 18 months and 3½ years. Aggressive children were described by their mothers as quick to hit, bite, fight, kick and bully.
Dr. Séguin conceded that only a small sample of children fit the criteria of having a smoking mother with antisocial behaviour. Further research is needed, he said.
The researchers also found heavy smokers with annual incomes of less than $40,000 had a 40-per-cent chance of having aggressive children, compared with 25 per cent for mothers who were moderate or non-smokers. But when family income was greater than $40,000, the gap between heavy smokers and the other two groups fell to 8 per cent.
Even when factors such as divorce, a mother's level of education and her age during pregnancy were accounted for, the effect of heavy smoking leading to aggression in children remained significantly high, the study found.
While there are programs in place that have been shown to benefit disadvantaged families where the mother is a heavy smoker, the researchers said more interventions and strategies are necessary to curb this deadly habit.
