Congenital Malformations Registry, New York State Department of Health, Albany, New York.
Department of Environmental Health Science, University at Albany School of Public Health, Rensselaer, New York.
Birth Defects Res. 2018 Nov 15;110(19):1468-1477. doi: 10.1002/bdr2.1385. Epub 2018 Oct 19.
Limited epidemiologic research exists on the association between weather-related extreme heat events (EHEs) and orofacial clefts (OFCs). We estimated the associations between maternal exposure to EHEs in the summer season and OFCs in offspring and investigated the potential modifying effect of body mass index on these associations.
We conducted a population-based case-control study among mothers who participated in the National Birth Defects Prevention Study for whom at least 1 day of their first two post-conception months occurred during summer. Cases were live-born infants, stillbirths, and induced terminations with OFCs; controls were live-born infants without major birth defects. We defined EHEs using the 95th and the 90th percentiles of the daily maximum universal apparent temperature distribution. We used unconditional logistic regression with Firth's penalized likelihood method to estimate adjusted odds ratios and 95% confidence intervals, controlling for maternal sociodemographic and anthropometric variables.
We observed no association between maternal exposure to EHEs and OFCs overall, although prolonged duration of EHEs may increase the risk of OFCs in some study sites located in the Southeast climate region. Analyses by subtypes of OFCs revealed no associations with EHEs. Modifying effect by BMI was not observed.
We did not find a significantly increased risk of OFCs associated with maternal exposure to EHEs during the relevant window of embryogenesis. Future studies should account for maternal indoor and outdoor activities and for characteristics such as hydration and use of air conditioning that could modify the effect of EHEs on pregnant women.
有关天气相关极端高温事件（EHEs）与口腔面裂（OFCs）之间关联的流行病学研究有限。我们估计了母体在夏季暴露于 EHEs 与后代 OFCs 之间的关联，并研究了体重指数对这些关联的潜在调节作用。
我们在参与国家出生缺陷预防研究的母亲中进行了一项基于人群的病例对照研究，其中至少有 1 天在受孕后前两个月的夏季度过。病例为口腔面裂的活产婴儿、死产和引产儿；对照组为无重大出生缺陷的活产婴儿。我们使用每日最大普遍表观温度分布的第 95 百分位和第 90 百分位来定义 EHEs。我们使用无条件逻辑回归和 Firth 的惩罚似然法来估计调整后的优势比和 95%置信区间，控制了母体社会人口统计学和人体测量学变量。
我们没有观察到母体暴露于 EHEs 与 OFCs 之间存在总体关联，尽管在东南气候区的一些研究地点，EHEs 的持续时间延长可能会增加 OFCs 的风险。OFCs 各亚型与 EHEs 之间没有关联。体重指数没有调节作用。
我们没有发现母体在胚胎发生相关窗口暴露于 EHEs 与 OFCs 风险显著增加相关。未来的研究应该考虑母体的室内和室外活动以及可能改变 EHEs 对孕妇影响的特征，例如水合作用和使用空调。
