Association between residential greenness and preeclampsia in Japan

Preeclampsia (PE), characterized by hypertension and organ dysfunction during pregnancy, is a leading cause of maternal and fetal mortality. Residential greenness has been reported to be inversely associated with a broad range of health outcomes. However, evidence on the association between residential greenness and PE remains limited, particularly among East Asian populations.

This study included 20,140 pregnancies among Japanese women from the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Residential greenness was assessed using the normalized difference vegetation index (NDVI) values calculated around the population-weighted centroid of each participant's postal code area. PE was identified using a rule-based phenotyping algorithm applied to medical records. Poisson regression with robust variance was used to estimate risk ratios (RRs) and confidence intervals, adjusting for maternal age, educational attainment, household income, urbanization status, and areal deprivation index.

Moderate NDVI levels were associated with a lower risk of PE than low NDVI levels (RR = 0.81 [95% confidence interval = 0.66, 1.00]). For high NDVI levels, the point estimate was below 1.00, but the association was not statistically significant (RR = 0.88 [0.69, 1.11]). No clear dose-response pattern emerged across tertiles (P for trend = 0.228). This inverse association was primarily observed in more-deprived areas. In subtype analysis, the associations were more evident in gestational hypertension and late-onset PE.

Moderate residential greenness was associated with a lower risk of PE compared with low residential greenness.