WASHINGTON — New research from Johns Hopkins University suggests pregnant women living near fracking wells in Pennsylvania are more likely to give birth prematurely or have high-risk pregnancies.

“Now that we know this is happening we’d like to figure out why,” said Brian Schwartz, lead researcher. “Is it air quality? Is it the stress? They’re the two leading candidates in our minds at this point.”

Schwartz and his colleagues studied the records of more than 9,000 mothers who gave birth in north and central Pennsylvania between 2009 and 2013. They compared the data with information about natural gas fracking wells.

The researchers found living among the most active quartile of fracking activity was associated with a 40 percent increase in premature birth and a 30 percent increase in reported high-risk pregnancies, which can mean factors like high blood pressure or excessive weight gain.

Johns Hopkins said the research was peer reviewed and funded by grants from the National Institutes of Health, the National Science Foundation and the Robert Wood Johnson Foundation.