Influence of residential greenness on adverse pregnancy outcomes: A systematic review and dose-response meta-analysis.

ABSTRACT

BACKGROUND: With the development of urbanization, there is a decreasing tendency for people contact with natural greenness. Whether maternal exposure to greenness has an impact on pregnancy complications and pregnancy outcomes remains to be confirmed. OBJECTIVES: To estimate the association and dose-response relationship between residential greenness and pregnancy outcomes. DATA SOURCES PubMed, Embase, Ovid, Scopus and Web of Science from inception to 1st December 2019 were searched. SYNTHESIS METHODS: The summary regression coefficient (ß) and odds ratio (OR) with corresponding 95% confidence interval (95%CI) were calculated. The linear dose-response relationship between greenness and adverse pregnancy outcomes was also investigated. RESULTS: Overall, 36 studies with a total of 11,983,089 participants were included. Birth weight was significantly higher in highest level of greenness exposure group compared to lowest level group (e.g. ß20.22, 95%CI13.50-26.93 at 100 m buffer). The odds of low birth weight (LBW) decreased in the highest level of group compared to lowest level group (e.g. OR0.86, 95%CI0.75-0.99 at 100 m buffer). The odds of small for gestational age (SGA) also decreased in the highest group (OR0.93, 95%CI0.88-1.00 at 100 m buffer). In addition, maternal exposure to greenness was associated with increased head circumference and decreased mental disorders. The dose-response models showed a 2% decrease risk of LBW per 0.1 normalized difference vegetation index (NDVI) increase within 300 m buffer (OR0.98, 95%CI0.97-0.99, P < 0.001) and a 1% decrease risk of SGA per 0.1 NDVI increase within 300 m buffer (OR0.99, 95%CI0.98-1.00, P = 0.037). No significant associations were found on preterm birth, gestational age, gestational diabetes mellitus, gestational hypertension or preeclampsia. CONCLUSIONS: This review confirms an inverse association between residential greenness and adverse pregnancy outcomes. Findings of our study provide evidences for pregnant women to increase greenness exposure.