Association between swimming lessons and rhinitis in school children: A nationwide birth cohort study

Objective: Swimming is one of the most popular extracurricular activities for school-aged children in Japan, but its potential impact on the development of rhinitis has been debated. This study aimed to investigate the relationship between swimming lessons and rhinitis onset in school-aged children. Methods: We used the data from the “Longitudinal Survey of Babies in the 21st Century,” a nationwide prospective birth cohort of 43,767 children born in Japan between May 10 and 24, 2010. We included follow-up surveys until the children were 9 years old, focusing on swimming lesson participation and rhinitis onset. Children were grouped based on swimming lesson frequency, and rhinitis was identified through parental reports. Poisson regression and generalized estimating equation (GEE) model were used for statistical analysis. Results: Swimming lessons and rhinitis showed a notable association in 18,150 children evaluated. The occasional and consistent swimming groups had increased rhinitis (adjusted risk ratio [aRR] = 1.11; 95 % confidence interval (CI), 1.02–1.22; aRR = 1.16; 95 % CI, 1.09–1.23), respectively. The GEE models were consistent with these findings, demonstrating the population average effects across repeated measures data (aRR = 1.13; 95 % CI, 1.08–1.18). Conclusion: This study found that swimming lessons may increase the risk of rhinitis in children, highlighting the need to reevaluate their implications for child health.