Associations between green space, air pollution and birthweight in Sydney Metropolitan Area, Australia

BACKGROUND AND AIM: Low birthweight is one of the most common pregnancy complications. Previous studies have shown that while higher quantities of green space are associated with higher birthweights, exposure to ambient air pollution is associated with lower birthweights. These results might be related since green space is theorized to buffer air pollution harms; however, evidence of interactions between these exposures on birthweight remains inadequate. Therefore, aim of this study was to investigate how the association between air pollution (NO2, PM2.5, SO2 and O3) term birthweight is affected by quantity of green space. METHODS: 79,430 births recorded in Sydney in 2016 and 2017 were included in the analysis. Multilevel linear regression with random intercepts for statistical area level 2 (SA2) were developed to assess association between air pollutants and birthweight. Furthermore, interaction terms between air pollutants and green space quantity were fitted in the model to examine potential effect modification. RESULTS:Higher PM2.5, NO2 and SO2 was associated with lower birthweight, while increase in O3 exposure was associated with higher birthweight (all p0.05). Higher green space quantity was associated with lower birthweight (p0.05). Interactions between green space quantity and NO2 and PM2.5 were identified (p0.05), indicating that increasing green space may help to mitigate harms of moderate levels of NO2 and PM2.5 on birthweight. CONCLUSIONS:Improving access to green spaces in cities may help support a healthy start in life by mitigating harms from certain air pollutants. Replication in different contexts and consideration of potentially contrasting results with different types of green space should be further investigated. KEYWORDS: Green space, Birth outcomes, air pollution