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Smoking during pregnancy increases asthma risk in school-age children

Mothers who smoked while pregnant increased their children’s risks for early and persistent wheezing and asthma when the children reached school age, according to study results.

“We do now show that the adverse effects of maternal smoking during pregnancy on wheezing patterns and asthma extends into school age, independent of paternal smoking, smoke exposure in childhood and birth characteristics,” Herman T. den Dekker, MD, of Erasmus Medical Center in the Netherlands, and colleagues wrote.

The researchers’ study was a part of the Generation R population-based prospective cohort study of pregnant women and their children in Rotterdam. The current study included 6,007 children born between April 2002 and January 2006.

Questionnaires were used to determine the frequency of maternal and paternal smoking during pregnancy, secondhand smoke exposure during childhood, wheezing patterns and asthma.

Continued maternal smoking during pregnancy, defined as smoking at least five cigarettes daily, was associated with increased risks for early (OR = 1.24; 95% CI, 1.01-1.52) and persistent wheezing (OR = 1.48; 95% CI, 1.13-1.95) and physician-diagnosed asthma (OR = 1.65; 95% CI, 1.07-2.55). There was no association, however, between increased airway resistance or fractional exhaled nitric oxide with prenatal maternal smoking.

Maternal smoking during the first trimester only or paternal smoking during pregnancy was not linked with airway interrupter resistance, fractional exhaled nitric oxide, wheezing or asthma.

“Although using validated questionnaires based on international guidelines, underreporting or over-reporting might have occurred, which might have led to misclassification of the outcomes resulting in either overestimations or underestimations of the true associations,” the researchers wrote. “Secondhand tobacco smoke exposure in childhood is associated with higher airway resistance, but this effect was partly explained by gestational age and weight at birth.” – by Ryan McDonald

Disclosure: The researchers report no relevant financial disclosures.