Posted on 4 November 2009
The findings were based on more than 14,000 mother and child pairs, all of whom were taking part in the Millennium Cohort Study of UK children born between 2000 and 2001 from families receiving child benefit.
Smoking during pregnancy may damage the developing structure and function of the foetal brain
Professor Kate Pickett
The study, led by Professor Kate Pickett from the Department of Health Sciences and the Hull York Medical School, is published in the Journal of Epidemiology and Community Health.
Mothers were categorised into light and heavy smokers, depending on how many cigarettes they smoked every day during pregnancy, and asked to score their three year old children’s behaviour.
Boys whose mothers smoked heavily throughout pregnancy were almost twice as likely to display behavioural problems. And the sons of light smokers were almost 80 per cent more likely to have hyperactivity-attention deficit disorders. The daughters of both light and heavy smokers were significantly more likely to display behavioural problems by the time they were three years old than girls whose mothers did not smoke.
Professor Pickett said: “Smoking during pregnancy may damage the developing structure and function of the foetal brain, which has already been shown to be the case in animals. The foetal development of boys may also be more sensitive to this kind of chemical assault, which might explain why boys are more likely to have behavioural problems than girls.
“Smoking may also boost the complex interactions between genetic and environmental factors, which contribute to a child’s development and behavioural patterns.”
The study found that girls whose mothers gave up during pregnancy were significantly less likely to have a combination of behavioural problems and hyperactivity-attention deficit disorders than girls whose mothers had never smoked, although these findings were based on small numbers.