Residential proximity to greenspace and human birth defects
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Background: Residential proximity to greenspace is associated with various health outcomes. We estimated associations between maternal perinatal residential proximity to greenspace and selected structural birth defects, including effect modification by neighborhood-level factors.
Methods: Data were from the National Birth Defects Prevention Study (1997-2011) and included 19,065 infants with at least one eligible birth defect (cases) and 8,925 without birth defects (controls) from eight Centers throughout the US. Participants provided their addresses throughout pregnancy which were systematically geocoded and linked to greenspace, US Census and US Department of Agriculture data. Greenspace was estimated using the normalized difference vegetation index (NDVI); average maximum NDVI was calculated within 100m and 500m concentric buffers surrounding each geocoded address at conception to estimate residential NDVI. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals comparing those in the highest and lowest quartiles of residential NDVI, and subsequently stratifying by rural vs. urban and neighborhood median income.
Results: After multivariable adjustment, for the 500m buffer, inverse associations were observed for Tetralogy of Fallot, secundum atrial septal defects, anencephaly, anotia/microtia, cleft lip ± cleft palate, transverse limb deficiency, omphalocele, and gastroschisis (ORs: 0.54-0.86). Significant heterogeneity was observed after stratification by rural vs. urban for hypoplastic left heart, coarctation of the aorta, and cleft palate with inverse associations only among those in rural areas. Stratification by neighborhood median income showed significant heterogeneity for secundum atrial septal defects, anencephaly, anotia/microtia, and anorectal atresia with inverse associations only among those in a high-income neighborhood (ORs: 0.45-0.81). Results were similar for 100m buffer analyses and similar patterns were observed for other defects, though results were less precise.
Conclusion: Our results suggest that perinatal residential proximity to more greenspace may contribute to a reduced risk of certain birth defects, especially among those living in rural or high-income neighborhoods.