Background 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 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.

Objective This 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.

Methods This 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 participant’s 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.

Results Moderate 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.

Conclusion Moderate 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.

The authors have declared no competing interest.

This work was supported by the Japan Agency for Medical Research and Development (AMED), Japan (Grant Nos. JP19gk0110039, JP17km0105001, JP21tm0124005, and JP21tm0424601), and by the Endowed Department of Traffic and Medical Informatics in Disaster, Tohoku Medical Megabank Organization, Tohoku University, which is funded through a donation from East Japan Railway Company (JR East).

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Ethical approval was obtained from the Ethics Committee of the Tohoku Medical Megabank Organization (2013-1-103-1), and all participants provided written informed consent for study participation.

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