Prenatal Exposure to Green Spaces and Stress Levels in Toddlers: Using Hair Cortisol as a Biomarker

Abstract Background Green spaces exposure is known to improve health by reducing stress and promoting well-being. However, few studies have explored its prenatal effects on children's health. This study examines the association between maternal prenatal green space exposure and hair cortisol levels in children at 2 years, aiming to understand how early environmental factors may influence development. Methods Participants were selected from an ongoing cohort study, the Longitudinal Examination across Prenatal and Postpartum Health in Taiwan, conducted in five hospitals in Taipei. Women at early prenatal visits and their partners were recruited, with follow-up to 6 years postpartum. Mid-pregnancy and 2-year postpartum data collected between September 2019 and March 2025 were analyzed. Normalized difference vegetation index (NDVI) within 250 to 2000 meters of the residence and hair cortisol concentration (HCC) were used to measure green space exposure and stress levels, respectively. Covariates were measured using self-administered questionnaires. A generalized linear model was used for examination. Results A total of 46 children were included in the analysis. After adjusting for covariates, higher maternal NDVI values during mid-pregnancy were significantly associated with lower HCC within 750 m (β = -0.17, p < 0.05), 1000 m (β = -0.16, p < 0.05), 1500 m (β = -0.18, p < 0.05), and 2000 m (β = -0.20, p < 0.01) buffers, and marginally associated with lower HCC in children within a 500 m buffer (β = -0.16, p < 0.1). Conclusions This study found that higher maternal green space exposure within larger buffer zones during pregnancy was associated with lower HCC in children at 2 years, highlighting the potential stress-buffering effects of prenatal green space exposure and underscoring the importance of natural environments during pregnancy. Key messages • Higher maternal exposure to green spaces during pregnancy is associated with lower stress levels HCC in 2-year-old children, suggesting a potential long-term stress-buffering effect. • Incorporating natural environments into urban planning may support maternal and child health by reducing early-life stress through prenatal green space exposure.