Green streets: Urban green and birth outcomes
Street trees may be more consistently beneficial for neonatal health than other varieties of local green space
A protective relationship between green space and birth outcomes has been documented in previous research. This study adds to the research base by including waterfront access (“blue space”) as a green space variable and by using street trees as an additional measure of residential greenness.
Pregnant mother and birth outcome data were gathered from the birth records of over 100,000 births for the year 2000 provided by the New York City Department of Health and Mental Hygiene. The Normalized Difference Vegetation Index (NDVI) — an objective measure of vegetation density in an area — was used as the primary metric for residential greenness. Additional measures of greenness included proximity to major green spaces and waterfront areas, and the number of street trees near the expectant mothers’ homes.
Data analysis investigated the relationship between adverse birth outcomes and variables reflecting residential greenness and access to major green spaces and waterfront areas. The analyses were conducted separately for women living in economically-deprived neighborhoods, as previous research found stronger associations between greenness and a decreased risk of adverse birth outcomes among women of lower socioeconomic status.
For this study, the deprived neighborhoods were, on average, less ‘green’ than non-deprived neighborhoods in terms of both NDVI values and street tree counts. The deprived neighborhoods were also more densely populated and tended to be closer to major roads and industrial land use. The deprived neighborhoods, however, tended to be in closer proximity to major green spaces and publicly accessible waterfront areas than non-deprived neighborhoods. This study found partial support for an association between residential greenness and birth outcomes, in that expectant mothers living in a neighborhood with fewer street trees tended to have an increased chance of a preterm birth. For expectant mothers in both deprived and non-deprived neighborhoods, no consistent significant associations between NDVI values, access to major green spaces, or waterfront access and birth outcomes were found.
These findings suggest that fine-grained, street-level vegetation is more beneficial for reducing the likelihood of preterm birth than a neighborhood’s raw vegetation density. Additionally, the similarity of the relationship between street trees and the odds of preterm birth among mothers in deprived areas and mothers in non-deprived areas suggests that nearby street trees could be protective against preterm birth for pregnant women regardless of their socioeconomic status.
This research highlights the importance of tree canopy in major cities and suggests that the planting and maintaining of street trees in economically disadvantaged neighborhoods has the potential to reduce environmental injustice.
Citation
Abelt, K., McLafferty, S., (2017). Green streets: Urban green and birth outcomes. International Journal of Environmental Research and Public Health, 14(7)
