Initial research into the effects of fracking on nearby residents has indicated that babies born near gas wells may have additional health risks; however, experts have cautioned that more research is needed before any conclusions can be drawn.

A study published in January in the journal Environmental Health Perspectives found that infants born to mothers who live near Colorado gas wells had more congenital heart defects, Bloomberg News reported.

"It's not really well understood how the environment interacts with genetics to produce these birth defects," said researcher Lisa McKenzie of the Colorado School of Public Health, as quoted by Bloomberg News. "We really need to do more study to see what the association is, if any, with natural gas development."

Another two studies, which haven't yet been peer-reviewed, showed evidence that babies born near Pennsylvania fracking locations were more likely to have low birth weight and therefore a higher chance of developmental problems.

The Colorado study was inconclusive since it failed to factor in the types of wells, local water quality or the mothers' genetics and behavior, according to the state Department of Public Health and Environment.

"I would tell pregnant women and mothers who live, or who at the time of their pregnancy lived, in proximity to a gas well not to rely on this study as an explanation of why one of their children might have had a birth defect," department director Larry Wolk said in a statement. "Many factors known to contribute to birth defects were ignored in this study."

Other research has linked low birth weight and anomalies in children to nearby drilling sites, but officials, industry advocates and scientists say it's too soon to tell if health risks and gas wells are connected.

"The data do tell us with more wells in the area there are more congenital heart defects, although there are a lot of limitations in the data and when we start looking at it more closely, that may or may not stand up," said McKenzie, who is planning another four-year study of pollution exposure that will be backed by the American Heart Association.

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