Geographic information assessment of maternal ambient health hazards and adverse birth outcomes in Canada

Small for gestational age (SGA: birth weight below 10th percentile), low birth weight at term (LBWT: birth weight below 2500 g at 37 or more weeks gestation), and preterm birth (PTB: born before 37 completed weeks gestation) are increasing in Canada, contribute to infant mortality and morbidity, and linked to the maternal exposome, including exposure to environmental hazards. We assessed province-level associations of birth events (n = 2,525,645; years 2006–2012) classified as SGA, LBWT, and PTB with prenatal exposures to industrial air pollutants (n = 228) and land activities (n = 8). We used GIS to spatially and temporally assign variables to the maternal residences at birth. We used logistic regression to identify which industrial chemical emissions or land activities had associations for thirteen provinces/territories. There were twenty-four chemicals, including ammonia, benzene, carbon monoxide, methyl ethyl ketone, and particulate matter – fifteen of which are known or suspected developmental toxicants that may affect SGA/LBWT/PTB. There were geographical differences in exposures and associations. The provinces that had statistically significant adverse birth outcome associations with: (i) only chemicals were in Ontario, Nunavut, and Yukon; (ii) predominantly chemicals were in Alberta, Newfoundland, and Québec; (iii) only land activities were in Manitoba, New Brunswick, Nova Scotia, Prince Edward Island, and Saskatchewan; and (iv) predominantly land activities were in British Columbia. Pollutants released to the air or potential hazards from land-based activities may be more important depending on where one lives.