To the Editor With great interest we read the article by Mitre et al.1 This study is, to our knowledge, the largest cohort in which the association between antibiotic treatment in early life and later allergic disorders is investigated, and we congratulate the authors for the extensive analyses of this cohort. For the cohort of Mitre et al,1 2 specific exclusion criteria drew our attention: the exclusion of children with allergic conditions in the first 6 months, as well as initial birth stay greater than 7 days. The first exclusion criterion may lead to the underestimated prevalence of allergic conditions, especially atopic dermatitis, which often occurs before age 6 months.2 Although we do understand that allergic conditions occurring before 6 months may obscure the effect of medication given after 6 months of age, we would like to know whether the authors can indicate how this may have changed the outcome of their study. For the second exclusion criterion, we would like to know whether this means that all infants who received antibiotics at birth for suspected neonatal infection were excluded. In 2018, we published the outcome of the Intestinal Microbiota Composition After Antibiotic treatment in Early Life study in which children who received antibiotics at birth were compared with children who did not.3 We found that antibiotics given in the first week of life significantly influence the outcome of wheezing in the first year of life. Moreover, we found a trend toward a higher incidence of allergic sensitization at age 1 year. Therefore, Mitre et al1 may have underestimated the risk for allergic disorders by excluding neonates with an initial birth stay greater than 7 days.