Early menarche and new onset of asthma: Results from the SAPALDIA cohort study.

Rationale: The association between early menarche and new onset of asthma warrants further investigation in those aged >30 years.

Objectives: Using data from the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA), we investigated whether early menarche was associated with new onset of asthma in women aged 18-60 years at baseline.

Methods: Our analysis included 2492 women with information on age at menarche and doctor-diagnosed asthma, who had been asthma free at the time of menarche and had complete covariate information. New onset of asthma was defined as newly reported doctor-diagnosed asthma which occurred at least one year after menarche. Asthma incidence and its association with early menarche was analysed using logistic regression, adjusting for age, atopy, smoking, BMI, parental asthma, urbanity, education and study area, and additionally stratifying by atopy and BMI.

Results: After adjustment of relevant confounders, women with early menarche did not have a significantly higher risk of onset of asthma than women without early menarche (OR 1.23, 95% CI 0.85-1.80). Young atopic women with early menarche appeared to have an increased risk of asthma compared with non-atopic women (OR 2.21, 95% CI 0.90-5.43); however, our results did not reach statistical significance.

Conclusion: We could not substantiate an association of early menarche with new onset of asthma in this Swiss population-based cohort aged 18-60 years at baseline. Future studies may need to prospectively assess age of menarche to investigate the association with new onset of asthma in those aged >30 years.