The discovery of antibiotics has had a tremendous influence on the treatment of infectious diseases leading to increased life expectancy (1). Antibiotics has been found to disrupt the development of the infant gut microbiome and been associated with weight changes (3). In antibiotic exposed mice, elevated levels of Firmicutes have been associated with increased energy harvest (4-5). Maternal antibiotic exposure could reach the infant through diffusion into breast milk leading to enhanced growth (6-8).
To investigate the association between antibiotic exposure through breastfeeding and infant growth in the first 10 months. Also, to examine if effects of antibiotics on growth were sex dependent.
The PANDORA-study used data from the Danish birth and prescription registries. In total 79,179 infants born 2004-20 were included. Exposure: any antibiotic prescribed to the mother while she was breastfeeding. Outcome: change in weight-for-length z-score between a baseline measurement and month 10 using WHO’s growth standards. Linear regression analysis was used to examine associations.
Infants exposed to antibiotics through breastfeeding had 0.14 SD units higher change in weight-for-length z-score than unexposed infants after adjustment for covariates (p<0.001), corresponding to a difference of 100 grams between exposed and unexposed infants at month 10. There was no evidence for an interaction between infant sex and antibiotics on growth (p=0.65). When stratified by breastfeeding duration, antibiotic exposure was associated with a significantly higher change in weight-for-length z-score among infants breastfed between 1-2 months (beta=0.20, p=0.04) and 1-4 months (beta=0.15, p=0.007), compared to unexposed infants. No significant differences were observed for exposures among infants breastfed between 3-4 months (beta=0.07, p=0.49) or 5-6 months (beta=0.04, p=0.67).
The results of this study show that exposure to antibiotics through breastfeeding during the first six months of life enhance growth in the first 10 months of life.