Residential proximity to tree canopy and preterm birth in Black women

Abstract

Background: There are marked racial disparities in obstetrical outcomes, with the incidence of preterm birth being the highest among non-Hispanic Black women. The presence of green space, such as forests and parks, is now widely viewed as a health-promoting characteristic of residential environments.

Objective: This study aimed to examine the association between the proximity of tree canopies to a prenatal residential address and the rates of preterm birth among non-Hispanic Black women in Milwaukee, Wisconsin.

Study design: This was a retrospective, case-control study utilizing hospital pregnancy records of self-identified non-Hispanic Black women. The addresses of the women, who delivered from 2011 to 2019, were geocoded to characterize the percentage of tree canopy surrounding the prenatal address using the National Land Cover Database. Circular residential buffers of 100, 150, 250, and 500 m were used to assess the exposure to tree canopy coverage in proximity to a prenatal address. Univariable and multivariable analyses were conducted to determine whether tree canopy percentage at 4 different proximity buffers, examined both in means and quartiles, was associated with preterm birth (birth at <37 weeks' gestation).

Results: Of the 2771 non-Hispanic Black women included in the study, 333 (12.0%) experienced preterm births. Less tree canopy coverage was significantly (P < .05) associated with preterm birth, irrespective of whether the coverage was quantified as a mean or by quartile. In the unadjusted and adjusted models, which adjusted for sociodemographic and clinical risk factors for preterm birth, a 10% increase in tree canopy coverage was associated with lower odds of preterm birth at all 4 buffers examined. When examining the green space by quartile, higher quartiles were associated with lower odds of preterm birth at the 100-, 150-, and 250 m buffers, but not at the 500 m buffer.

Conclusion: A higher percentage of tree canopy coverage in close proximity to the prenatal residential address is associated with lower odds of preterm birth among non-Hispanic Black women. These findings suggest that access to neighborhood green space is an important factor associated with preterm birth.

Keywords: Black; green space; non-Hispanic Black; preeclampsia; preterm birth; tree canopy.