Is the Relationship Between Breastfeeding and Childhood Risk of Asthma and Obesity Mediated by Infant Antibiotic Treatment?

Background: Studies of the protective effect of breastfeeding on asthma have not brought unequivocal results, and thus this issue remains controversial. Antibiotic use, known to increase asthma risk, may be involved in this relationship. The objective of this study was to assess the influence of breastfeeding duration on obesity and asthma risk in childhood and to test a mediating role of antibiotic use in infancy. Subjects and Methods: A cross-sectional anthropometric and questionnaire study was conducted on 1,277 schoolchildren 8 years of age. Data on weight status, asthma, breastfeeding duration, antibiotic administration in infancy, socioeconomic status, and lifestyle were analyzed. Multivariate standard and logistic regression and mediation analyses, controlling for confounders, were applied. Results: Total duration of breastfeeding was negatively related to the child's body mass index (p=0.038), fat percentage (p=0.030), and obesity risk (p=0.032). Dropping the variable of antibiotic use from the model made the breastfeeding duration a significant predictor of low asthma risk (p=0.027). Antibiotic treatment mediated the relationship between breastfeeding duration and asthma risk (Sobel's z=-2.61, p=0.009). Conclusions: Our findings support protective effects of longer duration of breastfeeding against obesity and asthma. We propose a new mechanism for a relationship between breastfeeding and asthma: shorter breastfeeding compromises infant health and thereby leads to antibiotic treatment, which in turn increases the risk of asthma.