By Valerie Volcovici

WASHINGTON (Reuters) – Women living near oil and gas production sites where natural gas is flared may be at a higher risk of giving birth preterm, a team of California researchers reported on Wednesday.

Analysis of more than 23,000 birth records from 2012 through 2015 reveals a 50% higher chance of preterm birth for women living within three miles (5 km) of Texas’ Eagle Ford shale basin than for women who lived farther away, according to the study.

“Our study finds that living near flaring is harmful to pregnant women and babies,” said co-author Jill Johnston, an environmental health scientist at the University of Southern California.

The research, published in the journal Environmental Health Perspectives, adds to evidence linking pollution with poorer pregnancy outcomes. Another study in June found a correlation between air pollution or higher outdoor temperatures and increased chances of having a preterm or stillborn baby.

Those findings, in the Journal of the American Medical Association, resulted from analyzing 70 studies covering 32 million births. It also found that black women were disproportionately at risk.

In the new study, by scientists at USC and UCLA, the association between preterm births and flaring proximity was seen only among Hispanic and Latina women, who made up 55% of the study population. No effect was seen among non-Hispanic White women, who comprised 37% of the total. Preterm babies are at higher risk of respiratory and cardiovascular illness, as well as developmental delays.

The team said it was the first to look at birth outcomes in relation to oil and flaring, which has seen a sharp increase in southern Texas’ Eagle Ford and other U.S. shale hubs.

Flares can release chemicals such as benzene, carbon monoxide and nitrogen oxides, along with fine particulate matter, heavy metals and black carbon.

The U.S. drilling industry flared or vented more natural gas in 2019 for the third year in a row, amid soaring production and a lack of regulatory efforts to curb the practice, according to state data and independent research estimates.

When oil prices are low, or when oil fields lack pipeline access, drillers tend to vent or flare gas, which can burn for weeks at a time.

(Reporting by Valerie Volcovici; Editing by Katy Daigle and Marguerita Choy)