Across the US, birth weights have declined as rates of natural gas production have increased, according to a new, first-of-its-kind national study.
While previous studies linked increases in hydraulic fracturing and natural gas production to lower birth weights in high-producing states such as Texas and Pennsylvania, this is the first to examine associations across states where extraction occurs.
“Those single-state studies are important, but you have to consider whether that information is generalizable to other parts of the country,” said Summer Sherburne Hawkins, an associate professor at the Boston College School of Social Work and senior author of the study. “With our study, we’re able to say that this is not unique to a specific state but is true across the country.”
The study, published in the journal Preventive Medicine Reports, found that every 10% increase in natural gas development in US counties is associated with a corresponding decrease in average birth weight of 1.48 grams, or 0.003 pounds. Among women of color, the effect was more significant: With every 10% increase in natural gas production, Asian babies’ average birth weight decreased by 2.76 grams, or 0.006 pounds and Black babies’ average birth weight decreased by 10.19 grams, or 0.02 pounds.
“That might not seem like a lot, but in some parts of the US, rates of natural gas production are increasing by thousands of percentage points over a very short period of time,” Hawkins said. “Lots of states are considering increasing production, and this research allows us to predict the potential implications for public health.”
Low birth weight is associated with higher rates of infant mortality, poor lung development, problems with growth and cognitive development, and increased risk of health problems later in life, including diabetes, heart disease, high blood pressure, and developmental disabilities.
To conduct the research, Hawkins and her colleagues looked at more than 33.8 million birth records from 2005 to 2018 from 1,984 counties in the 28 states where natural gas production occurred. They compared birth weights during that period with 9-month county-level averages of natural gas production at both conventional and hydraulic fracturing wells.
Jill Johnston, an associate professor at the University of Southern California Los Angeles who has researched the health effects of hydraulic fracturing but was not involved in this study, said the findings are significant.
“There have been very few national scale studies that look at these kinds of health impacts,” Johnston said. “It’s a real strength to be able to look more broadly across the US and see that these impacts are happening in many different communities, even if they haven’t been the focus of prior research like places with more intensive shale development.”