From the Department of Epidemiology, Boston University School of Public Health, Boston, MA.
Center for Climate and Health, Boston University School of Public Health, Boston, MA.
Epidemiology. 2024 Nov 1;35(6):864-873. doi: 10.1097/EDE.0000000000001774. Epub 2024 Jul 26.
Few epidemiologic studies have examined the association of ambient heat with spontaneous abortion, a common and devastating pregnancy outcome.
We conducted a case-crossover study nested within Pregnancy Study Online, a preconception cohort study (2013-2022). We included all participants reporting spontaneous abortion (N = 1,524). We defined the case window as the 7 days preceding the event and used time-stratified referent selection to select control windows matched on calendar month and day of week. Within each 7-day case and control window, we measured the mean, maximum, and minimum of daily maximum outdoor air temperatures. We fit splines to examine nonlinear relationships across the entire year and conditional logistic regression to estimate odds ratios (ORs) and 95% confidence interval (CI) of spontaneous abortion with increases in temperature during the warm season (May-September) and decreases during the cool season (November-March).
We found evidence of a U-shaped association between outdoor air temperature and spontaneous abortion risk based on year-round data. When restricting to warm season events (n = 657), the OR for a 10-percentile increase in the mean of lag 0-6 daily maximum temperatures was 1.1 (95% CI: 0.96, 1.2) and, for the maximum, 1.1 (95% CI: 0.99, 1.2). The OR associated with any extreme heat days (>95th county-specific percentile) in the preceding week was 1.2 (95% CI: 0.95, 1.5). Among cool season events (n = 615), there was no appreciable association between lower temperatures and spontaneous abortion risk.
Our study provides evidence of an association between high outdoor temperatures and the incidence of spontaneous abortion.
很少有流行病学研究调查环境热与自然流产之间的关系，而自然流产是一种常见且严重的妊娠结局。
我们开展了一项巢式病例交叉研究，该研究嵌套于 2013 年至 2022 年开展的一项妊娠研究在线孕前队列研究中。我们纳入了所有报告自然流产的参与者（N=1524）。我们将病例窗口定义为事件发生前的 7 天，并使用时间分层参照选择来选择在日历月和周几上相匹配的对照窗口。在每个 7 天的病例和对照窗口内，我们测量了每日最大户外空气温度的平均值、最大值和最小值。我们拟合样条曲线来检验整个年度的非线性关系，并使用条件逻辑回归来估计与温暖季节（5 月至 9 月）升温以及凉爽季节（11 月至 3 月）降温相关的自然流产的比值比（OR）和 95%置信区间（CI）。
我们发现，基于全年数据，户外空气温度与自然流产风险之间存在 U 形关联。当限制在温暖季节事件（n=657）时，滞后 0-6 天每日最大温度均值增加 10%的 OR 为 1.1（95%CI：0.96，1.2），最大温度的 OR 为 1.1（95%CI：0.99，1.2）。在之前一周出现任何极端高温日（>95%特定县分位数）的 OR 为 1.2（95%CI：0.95，1.5）。在凉爽季节事件（n=615）中，较低温度与自然流产风险之间没有明显关联。
我们的研究提供了证据表明，较高的户外温度与自然流产的发生率之间存在关联。
