ESPE Abstracts

Background: Antibiotics have direct effects on human gut, and infant’s intestinal microbiota is particularly vulnerable for perturbation. In mice it was shown that antibiotics increased body fat mass due to changes in composition of the intestinal microbial community. Therefore, antibiotic exposure during infancy could be associated with increase in body mass also in man.

Objective and hypotheses: To evaluate impact of antibiotic exposure, and its timing and type during infancy on weight and height at the age of 24 months or over.

Method: Retrospective longitudinal weight and height data were obtained for healthy 5.562 boys and 5.418 girls aged≥24 months, and BMI z-scores (zBMI) were calculated. Data on antibiotic administration from birth until 23 months of age was obtained from the Drug Purchase Register. Weight and height data in exposed and non-exposed children were compared using linear mixed models with perinatal factors as covariates.

Results: Exposed boys and girls were on average heavier (zBMI difference 0.13 S.D. (95% CI 0.07–0.19, P<0.001) and 0.05 S.D. (0.01–0.12, P<0.05) respectively) than non-exposed children at the age of ≥24 months. The most pronounced increase in zBMI was found in children with the first exposure before the age of 6 months (for boys 0.22 S.D. (0.13–0.31), and for girls 0.09 S.D. (0.00–0.19)) respectively. This effect was mainly due to exposure to macrolide antibiotics both in boys and girls (for boys 0.30 (0.14–0.46), and for girls 0.23 (0.04–0.42)).

Conclusion: Antibiotic exposure before 6 months of age has an increasing effect on body mass seen at≥24 months of age both in boys and girls.