A systematic review of maternal residential proximity to unconventional oil and Natural gas sites and congenital heart defects in newborns: Recommendations for future research

Various studies indicated that pregnant women living near UONG sites may be more likely to give birth to infants with CHDs due to exposure to air, water, and soil pollution generated by these sites. We systematically searched three English-language databases—PubMed, Scopus, and the Web of Science Core Collection—from their inception until September 21, 2024 to include all types of epidemiological studies that explored the associations between maternal residential proximity to UONG sites and CHDs in the US. We screened a total of 282 unique studies and included six cohort and case-control studies conducted between 1996 and 2017 for evidence synthesis. These studies, conducted in Texas (two studies), Colorado (two), Ohio (one), and Oklahoma (one), encompassed almost 4.5 million births (including 88,638 CHDs cases). All risk estimates were adjusted for socioeconomic status and behavioral factors. Overall, the findings vary significantly across studies in relation to different exposure categories and buffer distances. Four studies reported significant positive associations between proximity to UONG sites and increased odds of CHDs in newborns compared to pregnant women with no recorded exposure to these sites, with adjusted ORs ranging from 1.04 (95 % CI: 1.01–1.07) to 2.62 (95 % CI: 2.48–2.77). The inconsistencies across the included studies make it challenging to pool effect sizes and determine the true impact of these sites on CHD risk in newborns. We also believe that further research is needed worldwide, particularly in regions where these sites are prevalent, as the included studies are limited to the U.S. Our study highlights the need for simple and practical interventions to reduce associated exposures in these communities, as our findings reveal that fetuses of mothers living in proximity to UONG sites are at an increased risk of CHDs.