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Behaviour problems in children linked to smoking in pregnancy

Posted on 4 November 2009

Smoking during pregnancy significantly increases the risk of behavioural problems in children as young as three, according to research from the University of York.

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.


Notes to editors:

  • The research ‘Smoking in pregnancy and disruptive behaviour in 3-year-old boys and girls: an analysis of the UK Millennium Cohort Study’ can be read in full at
  • The Department of Health Sciences at the University of York is large and multidisciplinary, offering a broad range of taught and research programmes in the health and social care field. In the 2008 Research Assessment Exercise the University was rated equal first for the quality of its health services research and fourth for its nursing and midwifery research.

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