Background

Previous reports indicate an association between ambient temperature (Ta) and air pollution exposure during pregnancy and preterm birth (PTB). Nevertheless, information regarding the association between environmental factors and specific precursors of spontaneous preterm birth is lacking. We aimed to determine the association between Ta and air pollution during gestation and the precursors of spontaneous preterm parturition, i.e. preterm labor (PTL) and preterm prelabor rupture of membranes (PPROM).

Methods

From 2003 to 2013 there were 84,476 deliveries of singleton gestation that comprised the study cohort. Exposure data during pregnancy included daily measurements of temperature and particulate matter <2.5 μm and <10 μm, PM_2.5 and PM₁₀, respectively. Deliveries were grouped into PPROM, PTL and non-spontaneous preterm and term deliveries. Exposure effect was tested in windows of a week and two days prior to admission for delivery and adjusted to gestational age and socio-economic status. Poisson regression models were used for analyses.

Results

There is an association of environmental exposure with the precursors of spontaneous preterm parturition; PPROM was more sensitive to Ta fluctuations than PTL. This effect was modified by the ethnicity, Bedouin-Arabs were susceptible to elevated Ta, especially within the last day prior to admission with PPROM (Relative Risk (RR) =1.19 [95% CI, 1.03; 1.37]). Jews, on the other hand, were susceptible to ambient pollutants, two (RR=1.025 [1.010; 1.040]) and one (RR= 1.017 [1.002; 1.033]) days prior to spontaneous PTL with intact membranes resulting in preterm birth.

Conclusion

High temperature is an independent risk factor for PPROM among Bedouin-Arabs; ambient pollution is an independent risk factor for spontaneous PTL resulting in preterm birth. Thus, the precursors of spontaneous preterm parturition differ in their association with environmental factors.

中文翻译：

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影响早产和PPROM的环境因素的差异-基于人群的研究

背景

先前的报告表明，怀孕和早产期间的环境温度（Ta）与空气污染暴露之间存在关联。然而，缺乏有关环境因素与自然早产的特定先兆之间的关联的信息。我们旨在确定Ta和妊娠期空气污染与自然早产的先兆，即早产（PTL）和早产胎膜早破（PPROM）之间的关系。

方法

从2003年到2013年，该研究队列中有84,476例单胎妊娠分娩。怀孕期间的暴露数据包括每天测量的温度和颗粒物分别<2.5μm和<10μm，PM _2.5和PM ₁₀。分娩分为PPROM，PTL和非自发早产和足月分娩。在入院前一周和两天的窗口中测试暴露效果，并根据胎龄和社会经济状况进行调整。使用泊松回归模型进行分析。

结果

环境暴露与自发性早产的前兆有关。PPROM对Ta的波动比PTL更敏感。这种影响因种族而改变，贝都因人阿拉伯人易患Ta升高，尤其是在PPROM入院前的最后一天（相对风险（RR）= 1.19 [95％CI，1.03; 1.37]）。另一方面，犹太人易受环境污染物的影响，即自发具有完整膜的PTL导致早产的两天（RR = 1.025 [1.010; 1.040]）和一天（RR = 1.017 [1.002; 1.033]）。

结论

高温是贝都因人-阿拉伯人中PPROM的独立危险因素；环境污染是导致早产的自发PTL的独立危险因素。因此，自发性早产的前体与环境因素的联系不同。