Children who are given broad-spectrum antibiotics before the age of 2 may face a slightly higher risk of becoming obese during childhood, new research suggests.
Broad-spectrum antibiotics target a larger number of organisms than narrow-spectrum ones, according to the study.
"It is a reason to think about whether you need antibiotics, and which antibiotic you are picking," said lead researcher Dr. Charles Bailey, attending physician at Children's Hospital of Philadelphia and an assistant professor of clinical pediatrics at the University of Pennsylvania.
Bailey and his colleagues looked at the health records of nearly 65,000 children who were seen at clinics from 2001 through 2013. The researchers followed the children from birth to age 5. They tracked the height and weight of the children, and classified them as normal weight, overweight or obese.
The study authors found that 69 percent of the children were given antibiotics before age 2. On average, the children had 2.3 episodes of antibiotic use.
Children who had four or more exposures to antibiotics were 11 percent more likely to be obese than those who did not. The researchers also looked at whether the antibiotics prescribed were narrow-spectrum, which are recommended as first-line treatment of common childhood infections, or broad-spectrum.
"Kids who got broad-spectrum antibiotics had a 16 percent higher risk [of obesity than those who did not]," Bailey said.
No link was found between the narrow-spectrum drugs and obesity risk.
The researchers took into account other factors affecting obesity, such as insurance status, use of steroids and having an asthma diagnosis, and the association held.
The study was published in the Sept. 29 online edition of the journal JAMA Pediatrics.
Bailey and his team decided to look at the possible link between early antibiotic use and obesity risk because previous research has suggested that a person's intestinal microbe environment may be linked with obesity; antibiotic use may affect that environment.
"What we see here is an association," Bailey said. "We haven't proven cause and effect," he explained.
"For most kids, obesity is not the result of one thing they do or don't do," he said. And the 16 percent higher risk is not great, he acknowledged, but the many factors that may drive obesity risk add up.
Parents can ask a doctor who is recommending their young child take an antibiotic if the treatment is really needed. If it is, parents can ask if a narrow-spectrum antibiotic would do the job.
The study was funded by an unrestricted donation from the American Beverage Foundation for a Healthy America to the Children's Hospital of Philadelphia to support the hospital's Healthy Weight Program. The Healthy Weight Program directly funded the study, Bailey said.
The risk found is relatively small, but the finding is "certainly one more reason to be concerned that we should use [antibiotics] more carefully and more prudently," said Dr. Andrew Pavia, chief of pediatric infectious diseases at the University of Utah School of Medicine, in Salt Lake City.
If children really need an antibiotic, he said, "the good outweighs the harm."
He suggested asking these questions if your child's doctor is suggesting an antibiotic: "Do I really need [to give my child] an antibiotic or could we wait another day and see?" or "Is this the most narrow-spectrum to do the job?"