Background

Antibiotics are frequently prescribed to children, and may be an environmental influence that contributes to the increasing prevalence of childhood obesity. The aim of this study was to examine the effect of antibiotic use in the first year of life on child growth trajectories from birth to age 6 years including significant covariates.

Methods

Data from 586 children in the Infant Feeding Practices II (IFPS II) and 6 year follow-up study (6YFU) were included. Antibiotic exposures, weight and height measurements were collected from birth through the first 12 months, and then again at 6 years. Linear mixed effects growth modeling, controlling for exclusive breastfeeding, socio-demographic factors, smoking during pregnancy, gestational diabetes, and maternal pre-pregnancy weight status, was used to examine the association between antibiotic exposure and child growth trajectories through age 6 years.

Results

The majority of infants (60.58%) did not receive any antibiotics; 33.79% received 1-2 courses and 5.63% received 3 or more antibiotic courses during the first year. In the unadjusted model, children with 1-2 antibiotic exposures had a 0.17 (SE 0.08) higher rate of change in BMI z-score (BMIz) than children without any antibiotics, and children with ≥3 exposures had a 0.42 (SE 0.16) higher rate of change in BMIz (p = 0.009). Growth trajectory over time for those who had ≥3 antibiotics was greater than those without any antibiotics (p = 0.002).

Conclusions

Efforts to guide the judicious use of antibiotics should continue, particularly in the first year of life.