Link between early antibiotic exposure and weight gain in young children

A recent study has shown that antibiotics use in young children (under 24 months) could result in weight gain shown when the child reaches the age of 5…


A study conducted within the National Patient Centered Clinical Research Network (PCORnet) has found that antibiotic use at less than 24 months of age was associated with slightly higher body weight at 5 years of age.

Antibiotic overuse has been a major population health concern, primarily due to the dangers of increasing antibiotic resistance but, recently, interest in antibiotics’ effect on weight has emerged. Antibiotics disrupt the natural balance of intestinal bacteria or gut microbiome. Because the microbiome has important effects on the body’s metabolism and how food is digested, researchers have hypothesised that changes in weight might occur with microbiome disruptions.

PCORnet is an innovative research network that facilitates research across healthcare institutions through use of a process whereby each institution organises their data from electronic health records into a common form. The network also uses a variety of important innovations to protect patient privacy. Studies conducted in PCORnet also incorporate patient views in the design and conduct of the study.

This study used a sample of over 360,000 children from 35 institutions over the country. Researchers examined the relationship between antibiotic use among children less than two years old and their weight at around five years old, analysing such factors as: diagnosis of chronic conditions, number of antibiotic prescriptions given to children, and the specific types of antibiotics given.

Results show a small effect of antibiotic use and weight gain – less than a pound difference in weight for children of average height and weight receiving 4 or more courses of antibiotics, compared to children who received none. 

“While this small difference in weight might not be important for individual decisions regarding antibiotic prescribing by doctors and parents, these data may serve, in a small way, to further encourage efforts to decrease antibiotic use. The ability to conduct research on large, diverse populations in networks like PCORnet provides critical opportunities to examine important research questions, no matter the outcome.” said Jason Block, lead author and Associate Professor of Population Medicine at the Harvard Pilgrim Health Care Institute and Harvard Medical School.

The study was published in the journal Pediatrics.