Background: Prenatal maternal smoking has been associated with adverse respiratory effects in childhood such as lung deficits and wheezing, but results concerning asthma, hayfever, and atopic eczema are inconsistent.
Objective: In the present study, we investigate the effects of maternal smoking in pregnancy on asthma, hayfever, atopic eczema, and wheezing in the offspring up to the age of 14-18.
Methods: The study was based on a cohort of mothers enrolled during midwife visits around the 36th week of gestation in Odense and Aalborg, Denmark, 1984-1987. Singleton, live born children (n = 11,144) were followed-up in 2002 to obtain a childhood history of atopic diseases, by means of questionnaires to the parents. Multivariate logistic regression analyses for medical diagnoses of asthma, hayfever, atopic eczema, and symptoms of wheezing before the age of 3, were carried out on 7844 children.
Results: After adjustment for confounders, late prenatal smoke exposure was associated with wheezing, with an odds ratio (OR) of 1.2, and a 95% confidence interval (CI) of 1.1-1.5. Furthermore, slightly reduced estimates for hayfever (OR 0.8, CI 0.7-1.0) and atopic eczema (OR 0.8, CI 0.7-0.9) were obtained for children exposed in late pregnancy compared with non-exposed.
Conclusion: Late gestational smoke exposure was associated with wheezing but not with asthma, while null or even protective estimates were indicated for hayfever and atopic eczema. However, lack of control options for hereditary factors may have affected the results.