Doyle Mary-Alice, Leckning Bernard
Department of Social Policy, London School of Economics, London, United Kingdom.
Menzies School of Health Research, Charles Darwin University, Darwin, Australia.
PLoS One. 2025 Sep 3;20(9):e0330498. doi: 10.1371/journal.pone.0330498. eCollection 2025.
The impact of prenatal heat exposure on birth outcomes is well-established, but what is it about heat drives this relationship? Is it exposure to extreme temperatures, to moderate heat, or the confluence of heat and humidity? Despite the large body of research on heat exposure and birth outcomes, the literature lacks consistent measurement. This means we cannot extract practical recommendations around which heat conditions pose the greatest risk, and hence should be avoided during pregnancy. It also means we cannot predict the implications of climate change on neonatal health and healthcare needs at a population level. This paper has two goals: first, to demonstrate that our conclusions around the existence and magnitude of the impact of heat exposure vary dramatically with the choice of heat exposure metric, and second, to make general recommendations for how heat exposure should be measured in future. We present analysis from Australia's Northern Territory - a region spanning tropical and arid climates. We compare commonly used heat exposure metrics, alongside additional metrics supported by theory. We find that a metric based on 'bands' of exposure and incorporating daily minimum as well as maximum measures provides the best fit; this is consistent with our theoretical understanding that both moderate and extreme heat affect fetal development in different ways. Estimates based on our preferred heat metric suggest that the impact of prenatal heat exposure on preterm birth is orders of magnitude larger than what would be implied by some metrics commonly used in the literature. Our findings underscore the importance of getting the measure of heat right, particularly in tropical climates.
产前受热对出生结局的影响已得到充分证实，但究竟是热的哪些因素驱动了这种关系呢？是暴露于极端温度、适度高温，还是高温与高湿度的共同作用？尽管关于受热与出生结局已有大量研究，但文献中缺乏一致的衡量标准。这意味着我们无法得出关于哪些热环境风险最大、因此孕期应避免的实用建议。这也意味着我们无法在人群层面预测气候变化对新生儿健康和医疗需求的影响。本文有两个目标：第一，证明我们围绕受热影响的存在及程度得出的结论会因受热衡量指标的选择而有显著差异；第二，就未来应如何衡量受热给出一般性建议。我们展示了来自澳大利亚北领地的分析——该地区涵盖热带和干旱气候。我们比较了常用的受热衡量指标以及理论支持的其他指标。我们发现基于暴露“区间”并纳入每日最低和最高测量值的指标最适用；这与我们的理论认识一致，即适度高温和极端高温都会以不同方式影响胎儿发育。基于我们首选的热指标的估计表明，产前受热对早产的影响比文献中一些常用指标所暗示的要大几个数量级。我们的研究结果强调了正确衡量热的重要性，尤其是在热带气候地区。
