Wildfires in the Western United States are a growing and significant source of air pollution that is eroding decades of progress in air pollution reduction. The effects on preterm birth during critical periods of pregnancy are unknown. We assessed associations between prenatal exposure to wildland fire smoke and risk of preterm birth (gestational age < 37 weeks). We assigned smoke exposure to geocoded residence at birth for all live singleton births in California conceived 2007–2018, using weekly average concentrations of particulate matter ≤ 2.5 µm (PM) attributable to wildland fires from United States Environmental Protection Agency’s Community Multiscale Air Quality Model. Logistic regression yielded odds ratio (OR) for preterm birth in relation to increases in average exposure across the whole pregnancy, each trimester, and each week of pregnancy. Models adjusted for season, age, education, race/ethnicity, medical insurance, and smoking of the birthing parent. For the 5,155,026 births, higher wildland fire PM exposure averaged across pregnancy, or any trimester, was associated with higher odds of preterm birth. The OR for an increase of 1 µg/m of average wildland fire PM during pregnancy was 1.013 (95 % CI:1.008,1.017). Wildland fire PM during most weeks of pregnancy was associated with higher odds. Strongest estimates were observed in weeks in the second and third trimesters. A 10 µg/m increase in average wildland fire PM in gestational week 23 was associated with OR = 1.034; 95 % CI: 1.019, 1.049 for preterm birth. Preterm birth is sensitive to wildland fire PM; therefore, we must reduce exposure during pregnancy.

中文翻译：

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加利福尼亚州怀孕期间暴露于野火烟雾中的 PM2.5 和早产

美国西部的野火是一个日益严重的空气污染源，正在侵蚀数十年来在减少空气污染方面取得的进展。怀孕关键时期对早产的影响尚不清楚。我们评估了产前暴露于野外火灾烟雾与早产风险（胎龄 < 37 周）之间的关联。我们使用美国环境保护署社区多尺度空气质量模型中荒地火灾造成的颗粒物每周平均浓度≤2.5微米（PM），将2007年至2018年在加利福尼亚州怀孕的所有活单胎出生时的烟雾暴露分配给地理编码的居住地。逻辑回归得出早产的比值比 (OR) 与整个怀孕期间、每个三个月和怀孕每周的平均暴露量增加之间的关系。模型根据季节、年龄、教育程度、种族/民族、医疗保险和亲生父母是否吸烟进行了调整。对于 5,155,026 名新生儿来说，整个怀孕期间或任何三个月的平均野外火灾 PM 暴露量较高，与早产几率较高相关。怀孕期间平均野火 PM 增加 1 µg/m 的 OR 为 1.013 (95 % CI:1.008,1.017)。在怀孕的大部分时间里，野火PM与较高的几率相关。最强的估计出现在妊娠中期和晚期的几周内。妊娠第 23 周野火 PM 平均增加 10 µg/m 与 OR = 1.034 相关；早产的 95% CI：1.019、1.049。早产对野火 PM 很敏感；因此，怀孕期间一定要减少接触。