title: Residential greenness and birth outcomes: evaluating the influence of spatially correlated built-environment factors.
abstract: BACKGROUND
  Half the world's population lives in urban areas. It is therefore important to identify characteristics of the built environment that are beneficial to human health. Urban greenness has been associated with improvements in a diverse range of health conditions, including birth outcomes; however, few studies have attempted to distinguish potential effects of greenness from those of other spatially correlated exposures related to the built environment.
  
  
  OBJECTIVE
  We aimed to investigate associations between residential greenness and birth outcomes and evaluate the influence of spatially correlated built environment factors on these associations.
  
  
  METHODS
  We examined associations between residential greenness [measured using satellite-derived Normalized Difference Vegetation Index (NDVI) within 100 m of study participants' homes] and birth outcomes in a cohort of 64,705 singleton births (from 1999-2002) in Vancouver, British Columbia, Canada. We also evaluated associations after adjusting for spatially correlated built environmental factors that may influence birth outcomes, including exposure to air pollution and noise, neighborhood walkability, and distance to the nearest park.
  
  
  RESULTS
  An interquartile increase in greenness (0.1 in residential NDVI) was associated with higher term birth weight (20.6 g; 95% CI: 16.5, 24.7) and decreases in the likelihood of small for gestational age, very preterm (< 30 weeks), and moderately preterm (30-36 weeks) birth. Associations were robust to adjustment for air pollution and noise exposures, neighborhood walkability, and park proximity.
  
  
  CONCLUSIONS
  Increased residential greenness was associated with beneficial birth outcomes in this population-based cohort. These associations did not change after adjusting for other spatially correlated built environment factors, suggesting that alternative pathways (e.g., psychosocial and psychological mechanisms) may underlie associations between residential greenness and birth outcomes.
authors.affiliation: College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon, USA.
authors.forename: Perry
authors.initials: P
authors.lastname: Hystad
authors.forename: Hugh W
authors.initials: HW
authors.lastname: Davies
authors.forename: Lawrence
authors.initials: L
authors.lastname: Frank
authors.forename: Josh
authors.initials: J
authors.lastname: Van Loon
authors.forename: Ulrike
authors.initials: U
authors.lastname: Gehring
authors.forename: Lillian
authors.initials: L
authors.lastname: Tamburic
authors.forename: Michael
authors.initials: M
authors.lastname: Brauer
mesh_terms: D000397:Air Pollution / Q000009:adverse effects; D001724:Birth Weight; D001955:British Columbia / Q000453:epidemiology; D002947:Cities; D003247:Conservation of Natural Resources; D004777:Environment; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009622:Noise; D010944:Plants; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D012111:Residence Characteristics; D063809:Satellite Imagery; D012959:Socioeconomic Factors