The big idea — In a California study, we found that pregnant women living near active high-production oil and gas wells have an elevated chance of having low birth-weight babies. This finding adds to a growing body of research on potential public health impacts from oil and gas operations.
We analyzed the birth records of nearly 3 million babies born to people living within 6.2 miles (10 kilometers) of at least one oil or gas well in California’s Sacramento, San Joaquin Valley, South Central Coast, and South Coast regions – the state’s oil production epicenters – between 2006 and 2015.
Our analysis found that in rural areas, pregnant women who lived within 0.62 miles (1 kilometer) of the highest-producing wells were 40% more likely to have low birth-weight babies compared to pregnant women living farther away from wells or near inactive wells only. We also found that rural women living near the highest-producing wells were 20% more likely to have babies who were small for their gestational age, which is an indication of reduced fetal growth.
Among full-term births, babies born to rural women living within 0.62 miles of a well were 1.3 ounces (36 grams) smaller, on average, than those of their counterparts. This decrease in birth weight may seem minor from an individual clinical perspective, but such a downward shift at the population level can have significant implications for overall neonatal and infant health.
Finally, in urban areas, we found that pregnant women living close to high-production wells had a 4% higher risk of having a small-for-gestational-age baby.
Overall, these patterns persisted even after we took into account known risk factors for poor birth outcomes, such as maternal age, educational attainment, access to prenatal care, race/ethnicity, neighborhood-level socioeconomic status, and other sources of air pollution.
Los Angeles is home to the largest urban oil fields in the U.S., with many wells just feet away from homes and parks.
Why it matters — Oil and gas production has been a major U.S. industry for over a century. Today the United States is the largest petroleum producer in the world. Over the past several decades, new extraction technologies such as hydraulic fracturing (“fracking”) have significantly increased the scale of production in states including Pennsylvania, Colorado, and Texas.
Potential local impacts of oil and gas development include air, water and soil pollution, and excessive nighttime light and noise from well pad construction, truck traffic, drilling, pumps, gas flaring and other processes.
Studies in Pennsylvania, Colorado, Texas and Oklahoma have found that living near active oil and gas wells may put pregnant women at higher risk of having low birth-weight babies, premature births and babies that are small for their gestational age.
California’s unique oil and gas infrastructure dates back to the early 1900s. As of 2017, the state was one of the top five producers of crude oil in the country, although production levels are declining.