Expectant parents worry about having a healthy baby and whether their new child will have any future health problems. A baby’s environmental surroundings at the time of pregnancy, and even after they give birth, play a key role in the development of the fetus. According to a recent study published in the journal Environmental Health Perspectives, babies born near fracking sites are 30 percent more likely to have birth defects.

Each year, 150,000 babies are born with birth defects in the U.S. The March of Dimes says 60 to 70 percent of abnormalities of structure, function, or body metabolism that are present at the time of birth have unknown causes. The rest of birth defects can be the result of genetics, environment, or some combination of the two factors.

Environmental causes of birth defects have more to do with a mother’s health and exposure to chemicals or diseases during pregnancy. It remains unclear how many birth defects are related to environmental exposures, such as pesticides and pollutants in the air and water. However, polychlorinated biphenyls (PCBs), dioxins, and pesticides — endocrine-disrupting chemicals — have been linked to nervous system defects and developmental problems at birth. Also, living near a hazardous waste site has been identified as possible risk factor for birth defects ranging from spina bifida to Down syndrome, according to the Centers for Disease Control and Prevention.

As natural gas extraction rises in the U.S., activists and residents fear the potential health effects air pollutants may have on a newborn’s health. Now a team of researchers from the Colorado School of Public Health suggest mothers who live near a natural gas development can expose themselves to several potential teratogens — drugs or substances that interfere with the development of fetus. Benzene, a human carcinogen, and other air pollutants around natural gas wells have been known to cross the placenta from mother to fetus.

The relationship between a mother’s residential proximity to natural gas wells and its effect on birth defects was examined in more than 124,842 births from 1996 to 2009 in rural Colorado in the large cohort study. In the U.S., more than 15 million people now live within a mile of a gas well. The researchers hypothesize living near hydraulic fracturing, or fracking sites, may increase the risk of some birth defects.

The distance between natural gas well counts within a 10-mile radius of maternal proximity was used to estimate maternal exposure to natural gas development. This was used to estimate associations with birth defects such as congenital heart defect (CHD), neural tube defect (NTD), oral clefts, preterm birth, and low birth weight. The researchers did not take into account the mothers’ education, smoking, age, ethnicity, and the combination of smoking and alcohol use.

The National Heart, Lung, and Blood Institute says CHD usually involves problems in how the heart’s valves, walls, veins, or arteries develop in the womb, which can disrupt blood flow through the heart. CHD is known as the most common type of birth defect affecting eight out of every 1,000 newborns. Unlike CHD, NTD results in permanent deformities of the spinal cord or brain, occurring during the first month of pregnancy, or before a woman knows she is pregnant. They happen in about 3,000 pregnancies each year.

The findings revealed the prevalence of CHD and NTD was greater for mothers who lived a five and 10-mile radius to fracking sites. Babies born to mothers living in areas with a high density of wells — more than 125 wells per mile — were more than twice as likely to have NTD as those living with no wells within a 10-mile radius. These children were also found to have a 38 percent greater risk of CHD than those with no wells. The CHD rate for babies born to mothers living in areas with the most wells was 18 per 1,000 compared to 13 per 1,000 for those living with no wells within a 10-mile radius, while the NTD rate was 2.87 per 3,000 compared with 1.2 per 3,000 in areas with no wells, Environmental Health News reported.

These results highlight an increasing concern as the Colorado Oil and Gas Conservation Commission estimates 26 percent of more than 47,000 oil and gas wells in Colorado are located within 150 to 1,000 feet of homes. “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.

The reasoning behind the high rates of CHD and NTD could be attributed to the air pollutants emitted during natural gas development. Benzene and other hydrocarbons, particular matter, sulfur dioxide and nitrogen dioxide are released by trucks, drilling and pipelines near wells. However, Lisa McKenzie, lead researcher of the study, says she is more cautious about the NTD findings than the heart findings because the risk was only seen among women who lived in highly dense well areas, and because there were only 59 babies with NTD.

Several bodies of research has prompted agencies like the U.S. Environmental Protection Agency (EPA) to conduct an in-depth study on the potential impact of fracking on water resources, which could lead to harmful effects on nearby residents, including infants. The EPA’s investigation will help address concerns as more than 90 percent of Colorado’s wells are fracked. Five cities in Colorado have banned or placed a long-term halt on drilling after wells started appearing near schools and backyards.

Source: Adgate JL, Guo R, McKenzie LM, Newman LS, Savitz DA, and Witter RZ. Birth Outcomes and Maternal Residential Proximity toNatural Gas Development in Rural Colorado. Environmental Health Perspectives. 2014.