Association between prenatal and postnatal tobacco smoke exposure and allergies in young children.

BACKGROUND

Many studies have shown a positive association between environmental tobacco smoke (ETS) exposure and allergic disorders, whereas epidemiological evidence of the effect of maternal smoking during pregnancy on allergic diseases is inconsistent. We investigated the independent and joint effects of in utero exposure to maternal smoking and postnatal ETS exposure at home on allergic disorders among Japanese children.

METHODS

Study subjects were 1951 children aged 3 years. Data on maternal smoking during pregnancy and postnatal exposure to ETS at home, allergic symptoms, and potential confounders were collected through the use of a questionnaire. Outcomes were defined according to the criteria of the International Study of Asthma and Allergies in Childhood (ISAAC).

RESULTS

The prevalence values of symptoms of wheeze, asthma, and eczema in the previous 12 months were 22.0%, 8.8%, and 17.2%, respectively. We found that postnatal ETS exposure at home in the absence of in utero exposure to maternal smoking was associated with a higher prevalence of wheeze (adjusted odds ratio (OR) = 1.30, 95% confidence interval (CI): 1.01-1.67). In contrast, in utero exposure without subsequent postnatal ETS exposure at home or exposure to postnatal ETS at home in addition to in utero exposure to maternal smoking was not associated with the prevalence of wheeze. No measurable associations were observed between fetal, postnatal, or joint exposure and the prevalence of asthma or eczema.

CONCLUSIONS

Data from this study indicate that ETS at home may be associated with a higher prevalence of wheeze among young Japanese children.