中国城市“干岛”的早产风险及其与温度、臭氧交互效应的影响

近年来的研究表明，孕妇暴露于高温高湿环境可能增加早产的风险，而城市区域内湿度较低，尚未有研究深入探讨城市“干岛”（urban dry island, UDI）效应对早产的影响。本研究旨在探究个体水平UDI暴露与早产之间的是否存在保护作用，以及在城市高温、高臭氧暴露下UDI是否仍具有保护作用。本研究基于中国出生队列研究（CBCS）的阶段性数据（截至2020年12月的103040个出生记录），结合居住地址和相对湿度网格数据个体化评估UDI 指数，使用广义线性混合效应模型，调整潜在的混杂因素，如母亲特征和环境因素，来评估UDI暴露与早产之间的关联。在距离分娩前21 d的时间范围内， UDI 指数对早产存在较为一致而显著的保护作用。滞后1周的UDI指数每降低一个四分位数间距，早产的风险降低10%（OR=0.90; 95%置信区间:0.85, 0.95）。交互作用分析中发现UDI可能可以在一定程度上减弱由高温暴露，高臭氧暴露带来的早产风险。分层分析显示，在30岁以上、社会经济地位较低和生活在绿化程度更高区域的孕妇中， UDI 的保护作用更弱。研究结论表明，城市“干岛”效应可能对早产具有一定的保护作用，而在30岁以上、社会经济地位较低和生活在绿化程度更高区域的孕妇受到的保护作用更弱，提示这些人群可能为城市母亲中的易感亚组群，对其制定有针对性的干预措施具有重要意义。

Recent studies have increasingly pointed to the potential risks that high temperature and humidity pose to pregnant women,particularly in increasing the likelihood of preterm birth. However, within urban areas, where humidity tends to be lower,the impact of the Urban Dry Island（UDI） effect on preterm birth remains underexplored. This study aims to investigate whether UDI exposure at the individual level offers any protective benefits against preterm birth and whether this protective effect persists even under conditions of high urban temperature and ozone exposure.This research is based on data from the China Birth Cohort Study（CBCS）, encompassing 103040 birth records up until December 2020. By integrating residential address data with gridded relative humidity data, the study individualizes the assessment of UDI exposure. The UDI index, a measure of dryness in urban environments, was calculated for each participant based on their specific location. To examine the relationship between UDI exposure and the risk of preterm birth, the study employed a generalized linear mixed-effects model. This model allowed for the adjustment of potential confounding factors, including maternal characteristics such as age, pre-pregnancy BMI, education level, ethnicity, secondhand smoke exposure, air purifier use, and environmental factors such as proximity to major roads, noise disturbance,residential NDVI level, and average temperature during pregnancy.The findings of this study reveal a consistent and significant protective effect of UDI exposure against preterm birth within the 21-day period leading up to delivery. Specifically, for every quartile decrease in the UDI index lagged by one week, the risk of preterm birth decreased by 10%（OR=0.90, 95% CI: 0.85, 0.95）. This suggests that lower humidity in urban areas may help reduce the likelihood of preterm birth. Additionally, interaction analyses indicated that UDI may partially mitigate the increased risk of preterm birth associated with high temperature and high ozone exposure.Further stratified analyses showed variations in the protective effect of UDI across different subgroups. Notably, the protective effect of UDI was weaker among pregnant women who were over 30 years old, had lower socioeconomic status,or lived in areas with higher levels of greenery（as indicated by NDVI）. These findings suggest that while the UDI effect may generally offer a protective benefit against preterm birth, certain populations within urban environments may be more vulnerable and receive less benefit from this effect.In conclusion, the Urban Dry Island effect appears to have a protective role against preterm birth, especially during the critical weeks leading up to delivery. However, the strength of this protective effect varies among different demographic groups. The weaker protection observed among older, socioeconomically disadvantaged, and greener neighborhood residents highlights these groups as potentially susceptible subpopulations within urban mothers. This suggests the importance of developing targeted interventions for these high-risk groups to better protect them against the adverse outcomes associated with urban environmental exposures during pregnancy. The study’s findings underscore the complex interplay between urban environmental factors and maternal health, providing valuable insights for public health strategies aimed at reducing preterm birth rates in urban settings.