Background Our hypothesis was that exposure to fine particulate matter (PM2.5) is related to abnormal cord insertion, which is categorized as a form of placental implantation abnormality. We investigated the association between exposure to total PM2.5 and its chemical components over the first trimester and abnormal cord insertion, which contributes to the occurrence of adverse birth outcomes. Methods From the Japan Perinatal Registry Network database, we used data on 83 708 women who delivered singleton births at 39 cooperating hospitals in 23 Tokyo wards (2013–2015). We collected PM2.5 on a filter and measured daily concentrations of carbon and ion components. Then, we calculated the average concentrations over the first trimester (0–13 weeks of gestation) for each woman. A multilevel logistic-regression model with the hospital as a random effect was used to estimate the odds ratios (ORs) of abnormal cord insertion. Results Among the 83 708 women (mean age at delivery = 33.7 years), the frequency of abnormal cord insertion was 4.5%, the median concentration [interquartile range (IQR)] of total PM2.5 was 16.1 (3.61) μg/m3 and the OR per IQR for total PM2.5 was 1.14 (95% confidence interval = 1.06–1.23). In the total PM2.5-adjusted models, total carbon, organic carbon, nitrate, ammonium and chloride were positively associated with abnormal insertion. Organic carbon was consistently, and nitrate tended to be, associated with specific types of abnormal insertion (marginal or velamentous cord insertion). Conclusions Exposure to total PM2.5 and some of its components over the first trimester increased the likelihood of abnormal cord insertion.

中文翻译：

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孕早期孕妇暴露于细颗粒物和脐带插入异常

背景 我们的假设是，暴露于细颗粒物 (PM2.5) 与脐带异常插入有关，这被归类为胎盘植入异常的一种形式。我们调查了在孕早期暴露于总 PM2.5 及其化学成分与异常脐带插入之间的关联，这有助于不良分娩结果的发生。方法 从日本围产期注册网络数据库中，我们使用了东京 23 个区（2013-2015 年）的 39 家合作医院的 83708 名单胎分娩妇女的数据。我们在过滤器上收集 PM2.5 并测量碳和离子成分的每日浓度。然后，我们计算了每个女性在妊娠前三个月（妊娠 0-13 周）的平均浓度。使用医院作为随机效应的多级逻辑回归模型来估计异常脐带插入的优势比 (OR)。结果 83 708 名妇女（平均分娩年龄 = 33.7 岁）中，脐带异常插入的频率为 4.5%，总 PM2.5 的中位浓度 [四分位距 (IQR)] 为 16.1 (3.61) μg/m3，总 PM2.5 的每个 IQR 的 OR 为 1.14（95% 置信区间 = 1.06-1.23）。在总 PM2.5 调整模型中，总碳、有机碳、硝酸盐、铵和氯化物与异常插入呈正相关。有机碳和硝酸盐往往与特定类型的异常插入（边缘或绒毛状索插入）有关。结论 暴露于总 PM2。