Association Between Residential Greenness and Preeclampsia in Japan: The TMM BirThree Cohort Study

BackgroundPreeclampsia (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 negatively associated with a broad range of health outcomes, such as mental illness and cardiovascular disease. However, evidence on the association between residential greenness and PE remains limited, particularly among non-European populations. ObjectiveThis study aimed to investigate the association between residential greenness and PE among pregnant women in Japan, considering urbanization status and the timing of PE onset. MethodsThis study included 21,816 pregnant women from the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study, conducted in Miyagi Prefecture, Japan. Residential greenness was assessed using the Normalized Difference Vegetation Index (NDVI) values calculated from the center of each participants postal code area. PE was identified using a rule-based phenotyping algorithm applied to medical records. Logistic regression analyses were conducted to estimate odds ratios (ORs) and confidence intervals (CIs), adjusting for geographical variables, such as air pollution, urbanization status, area deprivation index, and individual-level confounders. ResultsModerate NDVI levels within a 200 m buffer were associated with a lower incidence of PE than low NDVI levels (OR: 0.79 [95% CI: 0.63-1.00]). High NDVI levels also suggested a negative association, but the results were not statistically significant (OR: 0.85 [95% CI: 0.64-1.14]), and no clear trend was observed (P for trend = 0.235). After adjusting for potential mediators, including psychological distress and physical activity, estimated values remained unchanged, but associations lost statistical significance. This association was primarily observed in non-urban areas and in late-onset PE. ConclusionModerate residential greenness was significantly associated with a lower incidence of PE compared to low residential greenness. These results suggest that moderate residential greenery is worth considering when choosing where to live during pregnancy.