ImportancePreterm birth (PTB) is associated with adverse health outcomes. The outcomes of heat exposure during pregnancy and the moderating association of greenness with PTB remain understudied.ObjectiveTo investigate associations between heat exposure, greenness, and PTB, as well as interactions between these factors.Design, Setting, and ParticipantsIncluded in this cohort study were births occurring in Sydney, New South Wales, Australia, between 2000 and 2020, retrieved from New South Wales Midwives Data Collection. Participants with incomplete or missing data on their residential address or those who resided outside of New South Wales during their pregnancy were excluded. Data were analyzed from March to October 2023.ExposuresGreenness measured using normalized difference vegetation index (NDVI) and tree cover derived from satellite images. Daily extreme heat and nighttime extreme heat were defined as above the 95th percentile of community- and trimester-specific daily mean temperatures and nighttime temperatures.Main Outcomes and MeasuresLogistic regression models estimated the independent association of extreme heat with PTB, adjusting for individual- and area-level covariates, season of conception, and long-term trend. An interaction term between extreme heat exposure and greenness was included to explore potential modification. With a significant interaction observed, the number of preventable heat-associated PTBs that were associated with greenness was estimated.ResultsA total of 1 225 722 births (median [IQR] age, 39 [38-40] weeks; 631 005 male [51.5%]) were included in the analysis, including 63 144 PTBs (median [IQR] age, 35 [34-36] weeks; 34 822 male [55.1%]). Compared with those without heat exposure, exposure to daily extreme heat and nighttime extreme heat in the third trimester was associated with increased risks of PTB, with an adjusted odds ratio (OR) of 1.61 (95% CI, 1.55-1.67) and 1.51 (95% CI, 1.46-1.56]), respectively (PTB rates: exposed, 4615 of 61 338 [7.5%] vs unexposed, 56 440 of 1 162 295 [4.9%] for daily extreme heat and 4332 of 61 337 [7.1%] vs 56 723 of 1 162 296 [4.9%] for nighttime extreme heat). Disparities in associations between extreme heat exposure and PTB were observed, with lower odds of PTB among pregnant individuals residing in greener areas. The associations between extreme heat exposure and PTB could be mitigated significantly by higher greenness. Improving NDVI and tree cover could reduce daily extreme heat-associated PTB by 13.7% (95% CI, 2.3%-15.1%) and 20.9% (95% CI, 5.8%-31.5%), respectively. For nighttime extreme heat-associated PTB, reductions were 13.0% (0.2%-15.4%) and 17.2% (4.1%-27.0%), respectively.Conclusions and RelevanceResults of this large birth cohort study suggest that extreme heat exposure was adversely associated with PTB, with greenness playing a moderating role. Increasing greenness levels in residential communities could prevent heat-associated PTBs. These findings emphasize the importance of integrating heat mitigation strategies and improving green space in urban planning and public health interventions.

中文翻译：

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澳大利亚的高温暴露、早产和绿色的作用

重要性早产 (PTB) 与不良健康结果相关。怀孕期间热暴露的结果以及绿色与 PTB 的调节关系仍有待研究。目的调查热暴露、绿色和 PTB 之间的关联，以及这些因素之间的相互作用。设计、设置和参与者本队列研究中包括出生2000 年至 2020 年间发生在澳大利亚新南威尔士州悉尼的事件，取自新南威尔士州助产士数据收集。居住地址数据不完整或缺失的参与者或怀孕期间居住在新南威尔士州以外的参与者被排除在外。数据分析时间为 2023 年 3 月至 10 月。ExposuresGreenness 使用归一化植被指数 (NDVI) 和卫星图像中的树木覆盖率进行测量。每日极端高温和夜间极端高温定义为社区和三个月特定日平均气温和夜间温度的 95% 以上。主要结果和措施Logistic 回归模型估计极端高温与 PTB 的独立关联，并根据个人和地区进行调整水平协变量、受孕季节和长期趋势。包括极端高温暴露和绿色度之间的相互作用项，以探索潜在的修改。通过观察到显着的相互作用，估计了与绿色相关的可预防的热相关 PTB 的数量。 结果 共有 1 225 722 名新生儿（中位 [IQR] 年龄，39 [38-40] 周；631 005 名男性 [51.5%] ]）纳入分析，其中包括 63 144 名 PTB（中位 [IQR] 年龄，35 [34-36] 周；34 822 名男性 [55.1%]）。与没有暴露于高温的患者相比，妊娠晚期暴露于每日极端高温和夜间极端高温与 PTB 风险增加相关，调整后的比值比 (OR) 为 1.61 (95% CI，1.55-1.67) 和 1.51 (95% CI，1.55-1.67)。 95% CI, 1.46-1.56]）（PTB 率：暴露，61 338 例中的 4615 例 [7.5%] 与未暴露例相比，每日极端高温为 1 162 295 例中的 56 440 例 [4.9%]，以及 61 337 例中的 4332 例 [7.1%] ] vs 56 723 of 1 162 296 [4.9%]（夜间极端炎热）。观察到极端高温暴露与 PTB 之间的关联存在差异，居住在绿化地区的孕妇发生 PTB 的几率较低。较高的绿色度可以显着减轻极端高温暴露与 PTB 之间的关联。改善 NDVI 和树木覆盖率可以将每日与极端高温相关的 PTB 分别减少 13.7% (95% CI, 2.3%-15.1%) 和 20.9% (95% CI, 5.8%-31.5%)。对于夜间极端高温相关的 PTB，降低率分别为 13.0% (0.2%-15.4%) 和 17.2% (4.1%-27.0%)。 这项大型出生队列研究的结论和相关性结果表明，极端高温暴露与PTB，其中绿色度起着调节作用。提高住宅社区的绿化水平可以防止与热相关的 PTB。