Smoking exposure and allergic sensitization in children according to maternal allergies

Although the negative impact of environmental tobacco smoke (ETS) on airway diseases in children is well known, the effect of ETS on allergic sensitization is still debated.

To evaluate how maternal allergies modulate the effect of tobacco exposure on allergic sensitization in childhood.

Of 9000 children in grades 4 and 5 selected in 6 cities in France, 7798 participated in a survey that consisted of an epidemiologic questionnaire, skin prick testing to common allergens, and skin examination for eczema. Tobacco exposure was obtained from parent questionnaires.

Twenty-five percent of the children had allergic sensitization, 25.2% had eczema, 11.6% had allergic rhinitis, 9.9% had asthma, and 8.3% had exercise-induced asthma. Twenty percent of the children were exposed to tobacco in utero. Maternal exposure had a greater impact than paternal exposure on children's allergic sensitization. Prenatal exposure was more associated with sensitization than postnatal exposure. Children with maternal allergies and exposure to maternal ETS during pregnancy were at higher risk for sensitization to house dust mite (25.7% vs. 14.0%; odds ratio, 1.95; 95% confidence interval, 1.19-3.18; P = .006). In contrast, sensitization to food allergens was not associated with tobacco exposure.

Children exposed to maternal smoking had a higher risk of sensitization to house dust mite, especially when the mothers were allergic.