Although children born to mothers who smoked during pregnancy are known to be at increased risk of developing asthma, ?few studies have investigated the role of active cigarette smoking on asthma onset during adolescence?, the researchers explain in the American Journal of Respiratory and Critical Care Medicine.
To address this, Dr Frank Gilliland, from the University of Southern California at Los Angeles, and colleagues monitored 2609 children who were aged between 8 and 15 years at the start of the study and had no previous history of asthma or wheezing.
During annual school visits, the researchers collected information on each child?s medical history, cigarette smoking, exposure to second hand smoke and any new diagnosis of asthma.
They found that children who regularly smoked, defined as an average of at least seven cigarettes a day in the week before the interview and at least 300 cigarettes in the previous year, were four times more likely to develop asthma than nonsmokers.
This increased risk was even higher for regular smokers whose mothers smoked during pregnancy. Indeed, such children were nine times more likely to develop the respiratory condition than non-smoking children whose mothers did not smoke during this time.
Dr Gilliland and team conclude: ?Effective tobacco control efforts focusing on the prevention of smoking in children, adolescents and women of childbearing age are urgently needed to reduce the number of these preventable cases of asthma.”
Commenting on the findings, Dr David Schwartz, director of the US National Institute of Environmental Health Sciences, added: “These findings suggest that the harmful effects of cigarette smoking are not limited to those who are long-term heavy smokers.
“The study results provide clear evidence of a link between short-term smoking and respiratory illness in adolescents and young adults.”