Parents may have a new reason to worry when their babies get sick, after a study earlier this year revealed a link to early use of antibiotics and childhood obesity.

The study, which was published in the journal Gastroenterology, determined that children given at least three courses of antibiotics before the age of 2 are more likely to become obese by the age of 4.

"Antibiotics have been used to promote weight gain in livestock for several decades, and our research confirms that antibiotics have the same effect in humans," Frank Irving Scott, a researcher from the University of Colorado's Anschutz Medical Campus, said in a news release. "Our results do not imply that antibiotics should not be used when necessary, but rather encourage both physicians and parents to think twice about antibiotic usage in infants in the absence of well-established indications."

Doctors often prescribe antibiotics to treat bacterial infections, including strep throat and other childhood illnesses. However, doctors have warned that the overuse of antibiotics can cause bacterial resistance.

A new study says giving children antibiotics before the age of 2 can lead to obesity by age 4. PHOTO ILLUSTRATION / Staff
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The new study, which cites more than 10 million prescriptions written each year to children without a clear need for the treatment, reveals another reason to be cautious.

"Our work supports the theory that antibiotics may progressively alter the composition and function of the gut microbiome, thereby predisposing children to obesity as is seen in livestock and animal models," Scott said in the release.

In the study, children who were exposed to more antibiotics early in life had a 25 percent relative risk of being obese at age 4, although the researchers noted that further study was needed to determine if that risk remained into adolescence or later in life.

Childhood obesity has doubled in children in the past three decades, according to the Centers for Disease Control and Prevention. Children who are obese often face health issues such as high blood pressure, bone and joint problems, diabetes, and social and psychological problems, and they are likely to remain overweight into adulthood.

This new answer to the questions surrounding childhood obesity may help parents and doctors in determining how to keep children healthier.