PCORnet Blog

PCORnet Study Results Show Small Link between Childhood Obesity and Antibiotics

As researchers dig into the science behind obesity, particularly in young children, we are learning some interesting things. For example, a growing body of evidence shows that our microbiome, a word for the collective trillions of bacteria and other microbes that live in our gut, may be a factor in how our body handles fat. Our gut bacteria play a role in keeping us healthy. So, what happens to our children’s developing microbiome when they take antibiotics that kill some of these gut bacteria as well as those causing an infection? Could there be a link between antibiotics and childhood obesity?


PCORnet launched the Obesity Observational Study of the short- and long-term effects of antibiotics on childhood growth in 2015 to find answers. The journal Pediatrics published a manuscript that shares some of the study’s results.


A link, but a slight one

Researchers have previously come to conflicting conclusions as to whether antibiotics at a young age have potential to affect weight. That’s why the PCORnet Obesity Observational Study, the largest study to date on this topic, is so significant. The study team examined data from 362,550 children between the ages of 4 and 5 across 35 PCORnet partner institutions. They looked at a wide scope of factors, including diagnosis of chronic conditions, number of antibiotic prescriptions given to children, and the specific types of antibiotics given.

Researchers found that antibiotic use in children less than 2 years of age was associated with only a slightly higher body weight at age 5. Specifically, the effect was less than a pound difference in weight for children of average height and weight who received four 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,” Jason Block, MD, MPH, principal investigator for the study and associate professor of Population Medicine at the Harvard Pilgrim Health Care Institute and Harvard Medical School, said in a news release about the findings.

A test of PCORnet’s capability

The Obesity Observational Study is one PCORnet’s first large studies. It demonstrates the network’s capacity for using large amounts of health data and patient partnerships to answer research questions. The study’s results are evidence of the PCORnet’s capability to deliver on its promise: research results that are faster, easier, less costly and, most importantly, relevant to patients’ needs.


Block said that the ability to conduct research with large, diverse populations in networks like PCORnet provides a critical opportunity to examine important research questions, no matter the outcome.


As the research community continues its efforts to unlock insights into childhood obesity, the PCORnet Obesity Observational Study results provide an important reference point and a stepping-stone to new discoveries.