Residential proximity to oil and gas development and risk of gestational diabetes mellitus

BACKGROUND: Oil and gas development-a highly prevalent industry in North America-is often located near residential communities. This industry produces a complex mixture of pollutants that may impact human health. Despite well-documented associations between residential proximity to oil and gas development and adverse birth outcomes, no study has examined gestational diabetes mellitus (hereafter, gestational diabetes)-a condition with long-term consequences for maternal-infant health. METHODS: We examined associations between residential proximity to active oil and gas development during pregnancy and gestational diabetes risk by using data from Pregnancy Study Online (PRESTO)-an internet-based preconception cohort study in the USA and Canada. We developed residential proximity measures for active oil and gas development at the estimated date of conception, including distance to the nearest site. For participants whose pregnancy progressed for ≥28 weeks of gestation, we evaluated diagnoses of gestational diabetes via self-administered questionnaires and birth records. We implemented log-binomial regression to estimate risk ratios (RRs) and 95% confidence intervals (CIs), adjusting for covariates, including stratification by pre-pregnancy body mass index (BMI) (<25.0, 25.0-29.9, ≥30.0 kg/m2) and parity (nulliparous, parous). RESULTS: Among 6285 participants, 8.6% of participants reported gestational diabetes. Residence within 5 km of active oil and gas development was not appreciably associated with gestational diabetes (RR: 1.07, 95% CI: 0.81, 1.40) compared with residence ≥20 km away. Associations did not vary by pre-pregnancy BMI or parity. CONCLUSION: We found no consistent evidence of an association between residential proximity to active oil and gas development at conception and the risk of gestational diabetes.