PURPOSE OF THE STUDY.
To assess the effect of exposure to secondhand smoke (SHS) on the development of asthma, rhinitis, and eczema during the first 16 years of life.
The study included 3798 children from a large birth cohort born between 1994 and 1996 in Stockholm County, Sweden.
This large prospective, population-based cohort study of patients from infancy to age 16 years used parent questionnaires to assess primarily secondhand smoke (SHS) exposure. Questions assessed smoking habits of both parents before and after birth, residential characteristics, parental allergic disease, socioeconomic status, and lifestyle factors. Outcome assessments were based on parental report of symptoms consistent with asthma, rhinitis, and eczema. Generalized estimating equation models were used to assess association between SHS exposure and allergic diseases up to 16 years of life. Logistic regression models examined various covariates including gender, parental history of allergic disease, and socioeconomic status.
Baseline characteristics between those who did and did not participate were comparable. Maternal smoking in utero was reported in 12.7% of families and parental smoking during infancy was reported in 20.8%. Exposure to maternal smoking in utero showed an elevated risk for development of prevalent asthma up to 16 years (odds ratio [OR] = 1.45; 95% confidence interval [CI], 1.15–1.83) but no significant overall effects for development of rhinitis or eczema. The influence of SHS exposure on elevated risk for asthma was strongest in the preschool age (1, 2, and 4 years). Exposure to parental smoke during infancy was associated with an overall elevated risk of prevalent asthma (OR = 1.23; 95% CI, 1.01–1.51), rhinitis (OR = 1.18; 95% CI, 1.01–1.39), and eczema (OR = 1.26; 95% CI, 1.09–1.45). Asthma and rhinitis risk was strongest in the preschool age, and eczema risk was strongest in school age and adolescence. SHS exposure throughout childhood indicated a positive overall association with prevalent eczema (OR = 1.14; 95% CI, 1.01–1.29) but not with asthma or rhinitis. Adjustments for socioeconomic indicators, birth weight, and gestational age at birth had minimal influence on results.
In utero and early life exposure to SHS has significant effects on the development of allergic diseases both in childhood and adolescence. The increased risk for asthma and rhinitis was strongest early in life, whereas eczema occurred later in school age or adolescence.
Although many studies indicate that the overall prevalence of parental smoking is decreasing, more work needs to be done to educate families about the harmful effects of SHS exposure in utero, infancy, and childhood.
- Copyright © 2015 by the American Academy of Pediatrics