If you've got a little one with a cold or earache, it may be tempting to reach for medications that might help your child feel better, but health experts have been warning for years about the overuse of antibiotics, which can cause an increase in antibiotic-resistant bacteria. Now that warning comes with another consequence. A new study has found that early exposure to certain types of antibiotics may increase a child's risk for obesity.

For the study, researchers from the Children’s Hospital of Philadelphia examined health care records from 2001 to 2003. Overall, researchers looked at the records for 64,580 children who were tracked from birth until 5 years of age.

Researchers found that nearly 70 percent of kids got oral antibiotics by the age of 2, with medications being prescribed for ear infections, bronchitis, and other common childhood ailments. On average, children were prescribed 2.3 rounds of antibiotics within the study period. Researchers found that children who were given antibiotics before age 2 were slightly more likely than their peers to become obese. 

The prevalence of obesity was 10 percent at 2 years of age, 14 percent at 3 years, and 15 percent at 4 years of age in all children. The more often the children took antibiotics, the more likely they were to become obese. Children who received the most antibiotics — four or more courses — were 11 percent more likely to become obese compared to kids who received none.

Obesity risk varied according to the type of antibiotic prescribed. Kids who received broad-spectrum antibiotics, which kill a wide range of bacteria, were 16 percent more likely to become obese.

Why would antibiotic use affect a child's risk for obesity?

Health experts are just beginning to understand the role of bacteria in the human body. Some research suggests that the bacteria in the gut may affect how we absorb and process calories. Thus, disturbing this process in young children could set them up for a lifetime of weight maintenance issues.

This study was published in the recent issue of Pediatrics.

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