Sex differences in the association between smoking exposure and prevalence of wheeze and asthma in 3-year-old children

Abstract

Objective

We examined independent and joint associations between prenatal and postnatal smoking exposure and the prevalence of wheeze and asthma among 3-year-old Japanese children. Sex differences were also investigated.

Methods

Smoking exposure, allergic symptoms, and potential confounding factor data were collected using a self-administered questionnaire. Wheeze was defined on the basis of the International Study of Asthma and Allergies in Childhood criteria. Physician-diagnosed asthma was considered to be present if a physician had diagnosed the child with asthma any time before the survey was administered.

Results

There were 6402 pediatric participants in this study. Maternal smoking throughout pregnancy and household smoking exposure during the first year of life were associated with an increased prevalence of wheeze among girls but not boys (adjusted odds ratio (OR) [95% CI] = 2.00 [1.13–3.42] and 1.34 [1.07–1.68], respectively). Girls exposed to both prenatal maternal smoking and postnatal household smoking exposure had a significantly higher prevalence of wheeze and physician-diagnosed asthma compared with girls without these exposures (adjusted OR [95% CI] = 2.06 [1.39–3.01] and 1.86 [1.01–3.26], respectively). No association was observed between perinatal smoking exposure and the prevalence of wheeze or asthma among boys. Significant interactions between sex and smoking exposure affecting wheeze and asthma were also found (p for interaction = 0.0003 and 0.01, respectively).

Conclusion

We found a positive association between perinatal smoking exposure and the prevalence of wheeze and asthma only among girls. Effects of perinatal smoking exposure on wheeze and asthma might be sex specific. Further research is required.

Keywords:

• Asthma
• child
• cross-sectional studies
• environmental tobacco smoke
• passive smoking
• wheeze

Acknowledgements

The authors thank the municipal governments that supported the KOCHS and all study participants.

Author’s contributions

KT, YM, CN, and MA contributed to the study concept and design as well as data acquisition. MA and KT were responsible for the analysis and interpretation of data and the drafting of the manuscript. YM assisted in manuscript preparation. All authors read and approved the final manuscript.

Ethics approval and consent to participate

The KOCHS was approved by the ethics committees at the Faculty of Medicine, Fukuoka University and Ehime University Graduate School of Medicine. Parents or guardians of participants provided written informed consent.

Declaration of interest

Keiko Tanaka and Yoshihiro Miyake were supported by Meiji Co. Ltd. The other authors declare that they have no competing interests.

Funding

This study was supported by JSPS KAKENHI (Grant number JP24390158), Meiji Co. Ltd., and the Food Science Institute Foundation. These organizations did not have any influence on the study design; the collection, analysis, or interpretation of data; the writing of the report; or the decision to submit the article for publication.

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.