ISGlobal, Barcelona, Spain.
Universitat Pompeu Fabra (UPF), Barcelona, Spain.
Environ Health Perspect. 2021 Oct;129(10):107001. doi: 10.1289/EHP8117. Epub 2021 Oct 13.
Exposure to heat during pregnancy has been associated with reduced fetal growth. Less is known about associations with cold and the potential for critical time windows of exposure.
We aimed to evaluate, in a national retrospective cohort, critical windows of susceptibility during pregnancy to extreme temperatures (low and high) and fetal growth, among 624,940 singleton term births in Israel during the period 2010-2014.
Temperature exposures were estimated using a spatially refined gridded climate data set with a 1-h and resolution. Percentiles of temperature were categorized by climatic zone for the entire pregnancy and by trimesters and weeks. Generalized additive models with the distributed lag nonlinear model framework were used to estimate unadjusted and adjusted associations between percentiles and categories of temperature and fetal growth markers: term [births after 36 weeks of gestational age (GA)] mean birth weight and term low birth weight (tLBW, term infants with birth weight below ).
After adjustment, extreme temperatures (percentiles) during the entire pregnancy were associated with a lower mean birth weight { vs. 41st-50th percentile: [95% confidence interval (CI): , )]; vs. 41st-50th percentile: ; 95% CI: , }. Similar inverse U-shaped patterns were observed for all trimesters, with stronger associations for heat than for cold and for exposures during the third trimester. For heat, results suggest critical windows between 3-9 and 19-34 GA-weeks, with the strongest association estimated at 3 GA-weeks (temperature vs. 41st-50th percentiles: ; 95% CI: , ). For cold, there was a consistent trend of null associations early in pregnancy and stronger inverse associations over time, with the strongest association at 36 GA-week ( vs. 41st-50th percentiles: ; 95% CI: , ). For tLBW, U-shape patterns were estimated for the entire pregnancy and third trimester exposures, as well as nonsignificant associations with heat for 29-36 GA-weeks. Generally, the patterns of associations with temperatures during the entire pregnancy were consistent when stratified by urbanicity and geocoding hierarchy, when estimated for daily minimum and maximum temperatures, when exposures were classified based on temperature distributions in 49 natural regions, and when estimated for all live births.
Findings from our study of term live births in Israel (2010-2014) suggest that exposure to extreme temperatures, especially heat, during specific time windows may result in reduced fetal growth. https://doi.org/10.1289/EHP8117.
孕期暴露于高温与胎儿生长受限有关。人们对低温暴露的关联以及潜在的关键暴露窗口期知之甚少。
我们旨在评估在以色列 2010-2014 年期间 624940 例足月单胎分娩的全国回顾性队列中，极端温度（低温和高温）与胎儿生长之间的孕期关键易感窗口期。
使用空间细化的网格化气候数据集估计温度暴露情况，分辨率为 1 小时。整个孕期按气候区、孕期和孕周对温度百分位数进行分类。使用广义加性模型和分布式滞后非线性模型框架，估计温度百分位数和类别与胎儿生长标志物之间的未经调整和调整关联：足月[孕龄（GA）36 周后分娩]平均出生体重和足月低出生体重（tLBW，出生体重低于第 41-50 百分位的足月婴儿）。
调整后，整个孕期的极端温度（百分位数）与较低的平均出生体重相关{与第 41-50 百分位相比：[95%置信区间（CI）：，）]}；与第 41-50 百分位相比：；95%CI：，}。所有孕期均呈现出类似的反 U 型模式，热暴露的关联强于冷暴露，且与孕晚期暴露的关联更强。对于热暴露，结果表明 GA 周 3-9 至 19-34 之间存在关键窗口期，GA 周 3 时关联最强（温度 与第 41-50 百分位相比：；95%CI：，）。对于冷暴露，孕早期的关联呈一致的无关联趋势，随着时间的推移呈负相关，GA 周 36 时关联最强（与第 41-50 百分位相比：；95%CI：，）。对于 tLBW，整个孕期和孕晚期暴露均呈现出 U 型模式，GA 周 29-36 时与热暴露无显著关联。一般来说，当根据城市规模和地理编码层次进行分层、当估计每日最低和最高温度时、当根据 49 个自然区域的温度分布对暴露进行分类以及当估计所有活产儿时，整个孕期与温度相关的关联模式保持一致。
本研究对以色列 2010-2014 年足月活产儿的研究结果表明，在特定窗口期暴露于极端温度，尤其是热，可能会导致胎儿生长受限。https://doi.org/10.1289/EHP8117.
