Antibiotic Use in Infancy and Odds of Being Overweight or Obese at Age 5: Weighing
LewisFirst, MD, MS, Editor in Chief, Pediatrics
There have been a number of studies noting a small but increased association between
antibiotic usage in infancy and toddlerhood and an increased likelihood of a child
becoming overweight or obese as they grow older. This might be due to alterations
in the microbiome. Often these studies have small numbers or not control for confounders,
raising questions about whether this relationship is real. This month, Block et al.
(10.1542/peds.2018-0290) offer a study involving 35 institutions and 362,550 infants who had height and weight
measured on the same day in their first year of life and then subsequently as they
got older up to age 5 years, looking at the association between antibiotic usage and
the odds of being overweight or obese while controlling for numerous confounders.
They looked at children with and without a complex chronic condition and found that
the odds of being overweight or obese was increased by 5% in their adjusted models
among children who received antibiotics in the first two years of life. The authors
also found that the more antibiotics used, the greater the odds for the association
(but even with 4+ courses of antibiotics in the first two years of life, the odds
ratio only increased to 1.10).
So, what does this mean? Is this a causal relationship that would caution us to be
even better stewards of antibiotic? To answer these questions, we asked Drs. Antti
Saari and Ulla Sankilampi, experts on this topic from Kuopio University in Finland
to share their thoughts in an accompanying commentary (10.1542/peds.2018-2692). The authors focus their comments on whether this association might be causal by
looking at what is needed to prove causality, including the strength of the association,
its consistency, specificity, temporality, dose dependence, plausibility and understanding
of biological mechanisms in terms of the Block et al. study and others. Their analysis
of these factors does suggest causality is strongly possible, but the clinical significance
of this causality is very small, given the small increases in the odds ratios found
in this study and others. The study and commentary provide much more than just a light-weight
look at this fascinating association and a possible contributor to weight gain in
children—so check both out and decide just how heavily or seriously you should take
the findings regarding counseling your families of children who are overweight or
obese as to whether or not to opt for antibiotics.