Pregnant women living near natural gas wells face a higher risk of giving birth to children with neurological and heart defects, a new study (pdf) shows.

Researchers from the Colorado School of Public Health examined birth defects among 125,000 babies born in small Colorado towns (50,000 people or less) between 1996 and 2009. In particular, they focused on the proximity between where the mothers lived and the location of natural gas wells.

Their research showed women residing near such wells were more likely to have babies with neural tube and congenital heart defects.

Specifically, babies born to mothers in areas with many wells (more than 125 per mile) were more than twice as likely to have spinal or brain defects—and had a 38% greater risk of congenital heart defects—than those living with no wells within 10 miles.

Both types of birth defects are considered fairly rare.

“Taken together, our results and current trends in natural gas development underscore the importance of conducting more comprehensive and rigorous research on the potential health effects of natural gas development,” the researchers wrote in the journal Environmental Health Perspectives.

An industry spokesperson, Dollis Wright, downplayed the study’s findings, noting researchers didn’t take some factors into account.

“They didn’t address things like prenatal care, socioeconomic status and access to health care, which can make all the difference in the world when you look at birth defects,” Wright told Environmental Health News.

But the researchers did take into account the mothers' education, smoking, age, ethnicity, smoking and alcohol use, Brian Bienkowski wrote at Environmental Health News.

What is it about the drilling sites that could be resulting in these birth defects? “One plausible mechanism could be … air pollutants emitted during development and [the]congenital heart defects, and possibly neural tube defects,” the study’s lead researcher, Lisa McKenzie, told the News.

“Benzene and other hydrocarbons, particulate matter, sulfur dioxide and nitrogen dioxide, are emitted by trucks, drilling and pipelines near the wells,” wrote Bienkowski. “Benzene previously has been linked to neural tube defects in other areas, including Texas, where exposure is high from petrochemical industries. Benzene and several other air pollutants around natural gas wells are known to cross the placenta from mother to the fetus.”

The study should cause communities to think twice about whether to create a potential danger to pregnant mothers, Environment Colorado associate Lindsey Wilson told the News. “The findings in this study clearly show how important it is that Colorado state officials allow communities to make their own decisions on whether or not to allow fracking within their borders,” she said.

-Noel Brinkerhoff, Danny Biederman

To Learn More:

New Study: Babies Near Gas Wells More Likely To Have Birth Defects (by Brian Bienkowski, Environmental Health News)

Birth Outcomes and Maternal Residential Proximity to Natural Gas Development in Rural Colorado (by Lisa M. McKenzie, Ruixin Guo, Roxana Z. Witter, David A. Savitz, Lee S. Newman, and John L. Adgate, Environmental Health Perspectives) (pdf)