Maternal residential proximity to unconventional gas development and perinatal outcomes among a diverse urban population in Texas

Objective To assess associations between unconventional natural gas development (UGD) and perinatal outcomes. Methods We conducted a retrospective birth cohort study among 158,894 women with a birth or fetal death from November 30, 2010-November 29, 2012 in the Barnett Shale, in North Texas. We constructed three UGD-activity metrics by calculating the inverse distance-weighted sum of active wells within three separate geographic buffers surrounding the maternal residence: <=(1/2), 2, or 10-miles. We excluded women if the nearest well to her residence was >20 miles. Metrics were categorized by tertiles among women with >= 1 well within the respective buffer; women with zero wells <= 10 miles (the largest buffer) served as a common referent group. We used logistic or linear regression with generalized estimating equations to assess associations between UGD-activity and preterm birth, small-for-gestational age (SGA), fetal death, or birthweight. Adjusted models of fetal death and birthweight included: maternal age, race/ethnicity, education, pre-pregnancy body mass index, parity, smoking, adequacy of prenatal care, previous poor pregnancy outcome, and infant sex. Preterm birth models included all of the above except parity; SGA models included all of the above except previous poor pregnancy outcome. Results We found increased adjusted odds of preterm birth associated with UGD-activity in the highest tertiles of the (1/2)-(odds ratio (OR) = 1.14; 95% confidence interval 1.03, 1.25), 2-(1.14; 1.07, 1.22), and 10-mile (1.15; 1.08, 1.22) metrics. Increased adjusted odds of fetal death were found in the second tertile of the 2- mile metric (1.56; 1.16, 2.11) and the highest tertile of the 10- mile metric (1.34; 1.04-1.72). We found little indication of an association with SGA or term birthweight. Conclusions Our results are suggestive of an association between maternal residential proximity to UGD-activity and preterm birth and fetal death. Quantifying chemical and non-chemical stressors among residents near UGD should be prioritized.