We thank Ludvigsson for his interest in our work and for providing additional insights. As noted, our joint works implicate the role of antibiotics in the development of inflammatory bowel disease (IBD), however, there are limitations as well as unique strengths to our study design which should be noted.1 2

Although confounding may exist, our prospective cohort study design limits this possibility. For example, if an individual is not prescribed an antibiotic course for the first 10 years of follow-up, they will initially contribute at-risk time to the ‘no antibiotic exposure’ group. If, however, they are then prescribed an antibiotic course, the following 1–5 years will contribute time to the ‘antibiotic exposure group.’ At the end of these …