Nicholas Institute of Environmental Policy Solution, Duke University, Box 90335, Durham, NC, 27708, USA.
Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Int J Biometeorol. 2019 Dec;63(12):1611-1620. doi: 10.1007/s00484-019-01773-3. Epub 2019 Jul 31.
Research on the impact of heat on pregnant women has focused largely on outcomes following extreme temperature events, such as particular heat waves or spells of very cold weather on pregnant women. Consistently, the literature has shown a statistically significant relationship between heat with shortened gestational age with studies concentrated largely in the western states of the USA or other nations. The association between heat and shortened gestational age has not been examined in the Southeastern US where maternal outcomes are some of the most challenging in the nation. Unlike previous studies that focus on the impacts of a single heat wave event, this study seeks to understand the impact of high heat over a 5-year period during the annual warm season (May-September). To achieve this goal, a case-crossover study design is employed to understand the impact of heat on preterm labor across regions in North Carolina (NC). Temperature thresholds for impact and the underlying relationships between preterm labor and heat are investigated using generalized additive models (GAM). Gridded temperature data (PRISM) is used to establish exposure classifications. The results reveal significant impacts to pregnant women exposed to heat with regional variations. The exposure variable with the most stable and significant result was minimum temperature, indicating high overnight temperatures have the most impact on preterm birth. The magnitude of this impact varies across regions from a 1% increase in risk to 6% increase in risk per two-degree increment above established minimum temperature thresholds.
对热对孕妇影响的研究主要集中在极端温度事件后的结果上，例如特定的热浪或非常寒冷天气对孕妇的影响。一致的是，文献表明热与缩短的妊娠龄之间存在统计学上显著的关系，这些研究主要集中在美国西部各州或其他国家。在东南部，热浪与缩短的妊娠龄之间的关联尚未得到研究，而东南部的产妇结局是全国最具挑战性的之一。与以前集中研究单次热浪事件影响的研究不同，这项研究旨在了解在每年温暖季节（5 月至 9 月）的 5 年期间高温对早产的影响。为了实现这一目标，采用病例交叉研究设计来了解北卡罗来纳州（NC）各地区高温对早产劳动的影响。使用广义加性模型（GAM）研究早产劳动与高温之间的关系。使用网格化温度数据（PRISM）来建立暴露分类。结果表明，高温对孕妇有显著影响，且存在区域差异。最稳定和最显著的暴露变量是最低温度，表明夜间高温对早产的影响最大。这种影响的幅度因地区而异，从每增加 2 度风险增加 1%到风险增加 6%不等，超过既定的最低温度阈值。
