Background: It has been hypothesized that antibiotic usage in early life could contribute to development of overweight in childhood. Studies have seen association between antibiotic usage and overweight in childhood. We aimed to investigate the relationship between antibiotic exposure in infancy and development of body mass index (BMI) and body composition.
Methods: A prospective mother-child cohort study of 738 pregnant women and their 700 children, Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010). Information on antibiotic exposure was collected by interviews. Height/length and weight measures were collected at age 1, 2, 3, 4, 5 and 6 years and body composition was determined by a dual-energy X-ray absorptiometry (DXA) scan at age 3.5 and 6 years.
Findings: 306 (46%) of the 661 children were exposed to antibiotics before 1 year of age. There were no differences in BMI z-score development at age 1-6 years between children exposed to antibiotics compared to unexposed: z-score difference, -0.06 (95%CI: -0.17;0.06), p = 0.33, and no sex-differences (p-interaction = 0.48). Children exposed vs. not exposed to antibiotics had comparable fat percentage at 6 years of age: log(mean difference), 0.60% (95%CI: -0.212 to 1.41), p = 0.15.
Interpretation: Children exposed to antibiotics had similar BMI, BMI z-score and body composition between 1 and 6 years of life compared to unexposed children. Our study does not support the hypothesis that antibiotic exposure in infancy leads to development of obesity in the first 6 years of life.
Funding: The Lundbeck Foundation, The Ministry of Health, Danish Council for Strategic Research and The Capital Region Research Foundation.