Infants under 6 months who use antibiotics may have weight problems throughout childhood

Alex Lange, a 4-month-old, was denied health insurance because he is in the 99th percentile for height and weight for a baby his age, making him technically obese, according to pediatric guidelines. (Some insurers consider obesity a preexisting condition for which they can limit or deny coverage, but the guidelines only apply to children ages 2 and older.) The breast-fed infant from Colorado was born at a normal 8 1/4 pounds and grew to 17 pounds in just a few months. After media attention, the insurance company reversed its decision and decided it would cover all healthy babies, no matter their weight.More from 11 ways to save money on healthy food

(CBS News) Could giving you baby antibiotics lead to a childhood filled with weight problems?

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A new study by NYU Langone School of Medicine researchers found that some children who used antibiotics tended to weigh more for their height than children who didn't take the medication. In particular, the children who took the drugs between birth to five months of age had a 22 percent higher chance of being overweight by the time they were 38 months.

"We typically consider obesity an epidemic grounded in unhealthy diet and exercise, yet increasingly studies suggest it's more complicated," study author Dr. Leonardo Trasande, an associate professor of pediatrics and environmental medicine at the NYU, said in the press release.

For the study, researchers looked at 11,532 children in the U.K. who had used antibiotics as a child. The children were part of the long-term study the Avon Longitudinal Study of Parents and Children (ALSPAC).

The participant pool was separated into three categories: those who had used antibiotics from birth to five months, from six to 14 months and from 15 to 23 months. Weights were recorded at 6 weeks, 10 months, 20 months, 38 months, and 7 years of age.

The children in the six month to 14 month group showed no significant difference in body mass indices (BMI) - a measure of obesity - from their counterparts who did not take antibiotics. Likewise, the 15 to 23 months, while they had greater BMIs for their age and gender by the age of 7, had no significant increase in being overweight or obese.

However, the group that took antibiotics from birth to five months showed consistent increases in BMI from 10 to 38 months.

The study appeared online on Aug. 21 in the International Journal of Obesity.

"For many years now, farmers have known that antibiotics are great at producing heavier cows for market," said Dr. Jan Blustein, professor of population health and medicine at the NYU School of Medicine, said in the press release. "While we need more research to confirm our findings, this carefully conducted study suggests that antibiotics influence weight gain in humans, and especially children too."

Physicians said this study may help warn doctors who are too quick to prescribe antibiotics.

"I think that generally antibiotics are quick, frequently overused by practitioners to treat viral infection," said Dr. Richard J. Deckelbaum, professor of nutrition, pediatrics, and epidemiology at Columbia University Medical Center, said to ABC News. "I think that practitioners have to be aware of these findings. It's fast to write a prescription rather that to wait through a viral infection. It's another cautionary paper about not overusing antibiotics in young children."

Antibiotic overuse has concerned many officials, including the World Health Organization (WHO) Director-General Dr. Margaret Chan. In statements she made at a conference called "Combating antimicrobial resistance: Time for action"in March 2012, she warned that because of drug-resistant pathogens, "Things as common as strep throat or a child's scratched knee could once again kill," she said.