Residential Proximity to Unconventional Oil and Gas Development and Birth Defects in Ohio

Background: Chemicals used or emitted by unconventional oil and gas development (UOGD) include reproductive/developmental toxicants. Associations between UOGD and certain birth defects were reported in a few studies, with none conducted in Ohio, which experienced a thirty-fold increase in natural gas production between 2010 and 2020. Methods: We conducted a registry-based cohort study of 965,236 live births in Ohio from 2010–2017. Birth defects were identified in 4,653 individuals using state birth records and a state surveillance system. We assigned UOGD exposure based on maternal residential proximity at birth to active UOG wells and a metric specific to the drinking-water exposure pathway that identified UOG wells hydrologically connected to a residence (“upgradient UOG wells”). We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for all structural birth defects combined and specific birth defect types using binary exposure metrics (presence/absence of any UOG well and presence/absence of an upgradient UOG well within 10 km), adjusting for confounders. Additionally, we conducted analyses stratified by urbanicity, infant sex, and social vulnerability. Results: The odds of any structural defect were 1.13 times higher in children born to mothers living within 10 km of UOGD than those born to unexposed mothers (95%CI: 0.98–1.30). Odds were elevated for neural tube defects (OR: 1.57, 95%CI: 1.12–2.19), limb reduction defects (OR: 1.99, 95%CI: 1.18–3.35), and spina bifida (OR 1.93; 95%CI 1.25–2.98). Hypospadias (males only) was inversely related to UOGD exposure (OR: 0.62, 95%CI: 0.43–0.91). Odds of any structural defect were greater in magnitude but less precise in analyses using the hydrological-specific metric (OR: 1.30; 95%CI: 0.85–1.90), in areas with high social vulnerability (OR: 1.27, 95%CI: 0.99–1.60), and among female offspring (OR: 1.28, 95%CI: 1.06–1.53). Conclusions: Our results suggest a positive association between UOGD and certain birth defects, and findings for neural tube defects corroborate results from prior studies.