Abstract

Background:

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.

Objectives:

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.

Methods:

Temperature exposures were estimated using a spatially refined gridded climate data set with a 1-h and $1{\text{-km}}^2$ 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 $\mathrm{2,500}\mathrm{g}$).

Results:

After adjustment, extreme temperatures (percentiles) during the entire pregnancy were associated with a lower mean birth weight {$\le 10\text{th}$ vs. 41st–50th percentile: $–56\mathrm{g}$ [95% confidence interval (CI): $–63\mathrm{g}$, $–50\mathrm{g}$)]; $>90\text{th}$ vs. 41st–50th percentile: $–65\mathrm{g}$; 95% CI: $–72\mathrm{g}$, $–58\mathrm{g}$}. 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 $>90\text{th}$ vs. 41st–50th percentiles: $–3.8\mathrm{g}$; 95% CI: $–7.1\mathrm{g}$, $–0.4\mathrm{g}$). 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 ($\le 10\text{th}$ vs. 41st–50th percentiles: $–2.9\mathrm{g}$; 95% CI: $–6.5\mathrm{g}$, $0.7\mathrm{g}$). 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.

Discussion:

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

中文翻译：

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以色列（2010-2014 年）624,940 名单胎足月新生儿的妊娠期和出生体重的高低环境温度：对潜在易感窗口的调查

摘要

背景：

怀孕期间暴露于高温与胎儿生长减少有关。关于与寒冷的关联以及关键暴露时间窗口的可能性知之甚少。

目标：

我们的目的是在一个国家回顾性队列中评估 2010-2014 年期间以色列 624,940 名单胎足月分娩在怀孕期间对极端温度（低温和高温）和胎儿生长易感性的关键窗口。

方法：

使用具有 1 小时和$1{\text{-公里}}^2$解决。温度的百分位数按整个孕期的气候带以及孕期和孕周进行分类。具有分布式滞后非线性模型框架的广义加性模型用于估计百分位数与温度和胎儿生长标志物类别之间的未调整和调整关联：足月 [胎龄 (GA) 36 周后出生] 平均出生体重和足月低出生体重（tLBW，出生体重低于$\mathrm{2,500}\mathrm{G}$）。

结果：

调整后，整个怀孕期间的极端温度（百分位数）与较低的平均出生体重相关{$\le 10\text{th}$与第 41-50 个百分位相比：$–56\mathrm{G}$[95% 置信区间 (CI)：$–63\mathrm{G}$,$–50\mathrm{G}$)];$>90\text{th}$与第 41-50 个百分位相比：$–65\mathrm{G}$; 95% 置信区间：$–72\mathrm{G}$,$–58\mathrm{G}$}。在所有孕期都观察到了类似的倒 U 形模式，与热的关联比对冷的关联性更强，在妊娠晚期的暴露与暴露的关联性更强。对于热量，结果表明关键窗口在 3-9 和 19-34 GA 周之间，最强的关联估计在 3 GA 周（温度$>90\text{th}$与第 41-50 个百分位数相比：$–3.8\mathrm{G}$; 95% 置信区间：$–7.1\mathrm{G}$,$–0.4\mathrm{G}$）。对于感冒，在妊娠早期存在一致的无效关联趋势，并且随着时间的推移具有更强的反向关联，在 36 GA 周时关联最强（$\le 10\text{th}$与第 41-50 个百分位数相比：$–2.9\mathrm{G}$; 95% 置信区间：$–6.5\mathrm{G}$,$0.7\mathrm{G}$）。对于 tLBW，估计整个妊娠期和妊娠晚期暴露的 U 形模式，以及与 29-36 GA 周的热量无显着关联。一般来说，当按城市性和地理编码等级进行分层时，在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时，以及对所有活体进行估计时，整个怀孕期间与温度的关联模式是一致的出生。

讨论：

我们对以色列足月活产的研究结果（2010-2014 年）表明，在特定时间窗内暴露于极端温度，尤其是高温下，可能会导致胎儿生长减少。https://doi.org/10.1289/EHP8117