Association of atopic multimorbidity with childhood pet exposure and caesarean section delivery: a retrospective study from the Lifelines Cohort Study.

The hygiene hypothesis suggests that reduced microbial exposure may contribute to the development of atopic diseases, whereas higher exposure may exacerbate symptoms and promote disease progression.

To investigate the association between multiple childhood environmental exposures and atopic multimorbidity, defined as atopic dermatitis (atopic dermatitis) accompanied by at least two other atopic comorbidities, including asthma, food allergy (food allergy) and allergic rhinitis (allergic rhinitis).