The Influence of Breastfeeding, Cesarean Section, Pet Animals, and Urbanization on the Development of Inflammatory Bowel Disease: Data from the Swiss IBD Cohort Study

Introduction: The pathophysiology of inflammatory bowel disease (IBD) is incompletely understood. Current concepts imply that environmental factors (EFs) trigger disease onset as well as flares in genetically susceptible individuals. Objective: The objective of this study is to analyze the association between IBD and various EFs, which may influence the pathogenesis of the disease. Methods: 2,294 patients from the Swiss IBD Cohort Study (SIBDCS) received a questionnaire regarding EF including mode of delivery, breastfeeding, animals in household, and place of residence. The control group comprised patients’ childhood friends, who grew up in a similar environment (“friends cohort”). Results: A total of 1,111 questionnaires were returned from SIBDCS patients (response rate: 48.4%). Breastfeeding for