Pregnant smokers risk fat teens
Email Print Normal font Large font Julie Robotham Medical Editor
June 21, 2006
CHILDREN whose mothers smoked while pregnant are 40 per cent more likely to be obese by their early teens, a study has found, providing the strongest evidence yet that exposure to tobacco before birth directly causes unhealthy weight gain.
The University of Queensland survey - of more than 3000 14-year-olds born in Brisbane in the early 1980s - also found smoking mothers' children were 30 per cent more likely to be overweight, said the research leader, Abdullah Al Mamun, a population health expert.
Scientists had previously documented a link between mothers' smoking and fatter children, although it was believed this might be because of worse diet among poorer people, who are also more likely to smoke.
But the Brisbane study found the children of smokers who resisted cigarettes while pregnant were no fatter than those whose mothers had never smoked, increasing suspicions that smoking in pregnancy may directly cause childhood obesity.
The researchers also noted whether children were breastfed, what they ate, how much TV they watched and their participation in sport, and found these factors made little difference to the link between mothers' smoking and their teenagers' weight.
The results "provide yet another incentive for pregnant women to be persuaded not to smoke and for young women to be encouraged to never take up smoking", wrote Dr Mamun in the American Journal of Epidemiology.
It was possible tobacco chemicals circulating in a developing infant's bloodstream might alter the way its body controlled appetite, but it would be difficult to tease out which of the more than 4000 might be responsible, said Dr Mamun, whose work was funded by the Federal Government's National Health and Medical Research Council. Recent evidence suggested nicotine might be a culprit.
An obestetrics and gynaecology professor at the University of Adelaide, Jeffrey Robinson, said genetic studies had shown wide individual variations in how tobacco exposure before birth affected people, and for many the obesity risk might be even more extreme.
A research dietitian at the Children's Hospital at Westmead, Sarah Garnett, said the link between maternal smoking and weight was significant but the increased risk was relatively small compared with other factors known to influence children's chance of unhealthy weight gain. If both parents were overweight, their child's chance of being overweight rose tenfold.
Article
Linear Mode
