LAUSR

Background: Prior studies suggest exposure to oil and gas development (OGD) adversely affects birth outcomes, but no studies have examined flaring—the open combustion of natural gas—from OGD. Objectives: We investigated whether residential proximity to flaring from OGD was associated with shorter gestation and reduced fetal growth in the Eagle Ford Shale of south Texas. Methods: We conducted a retrospective cohort study using administrative birth records from 2012 to 2015 (N=23,487) and satellite observations of flaring activity during pregnancy within 5km of maternal residence. Multivariate logistic and linear regression models were used to estimate associations between four outcomes (preterm birth, small-for-gestational age, continuous gestational age, and term birthweight) and exposure to a low (1–9) or high (≥10) number of nightly flare events, as compared with no exposure, while controlling for known maternal risk factors. We also examined associations with the number of oil and gas wells within 5km using data from DrillingInfo (now Enverus). Results: Exposure to a high number of nightly flare events was associated with a 50% higher odds of preterm birth [odds ratio (OR)=1.50 (95% CI: 1.23, 1.83)] and shorter gestation [mean difference=−1.9 (95% CI: −2.8, −0.9) d] compared with no exposure. Effect estimates were slightly reduced after adjustment for the number of wells within 5km. In stratified models these associations were present only among Hispanic women. Flaring and fetal growth outcomes were not significantly associated. Women exposed to a high number of wells (fourth quartile, ≥27) vs. no wells within 5km had a higher odds of preterm birth [OR=1.31 (95% CI: 1.14, 1.49)], shorter gestation [−1.3 (95% CI: −1.9, −0.8) d], and lower average birthweight [−19.4 (95% CI: −36.7, −2.0) g]. Discussion: Our study suggests exposure to flaring from OGD is associated with an increased risk of preterm birth. Our findings need to be confirmed in other populations. https://doi.org/10.1289/EHP6394