《经济学人》双语：炎热天气如何影响生育率？

原文标题：
Too darn hot
Fewer babies are born in the months following hot days
The effect is small but consistent
太热了
炎热天气过后几个月出生的婴儿数量减少
影响虽小但始终存在

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THE HOTTEST year on record, 2023, may not retain its title for long; 2024 already looks as though it may overtake it.
2023年作为有记录以来最热的一年，可能很快会被取代；2024年看起来极有可能取而代之。

As temperatures continue to rise, countries will scramble to prevent heat deaths and tackle extreme weather.
随着气温的持续攀升，各国将纷纷采取措施防止高温致死和应对极端天气。

But global warming also has much subtler effects—including, researchers suggest, on fertility.
但全球变暖也会产生更微妙的影响--研究人员认为，其中包括对生育能力的影响。

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A paper recently published in Population Studies, a journal, is the latest to document a relationship between extreme heat and babymaking.
最近发表在《人口研究》杂志上的一篇论文，是最新一篇研究极端高温与生育之间关系的论文。

It showed that the fertility rate in Spain fell roughly nine months after extremely hot days, echoing recent data from countries around the world.
该研究发现，西班牙的生育率在极端高温天气约9个月后下降，这与世界各国最近的数据相吻合。

Although this effect is generally small, it could grow as climate change accelerates.
尽管目前这种影响相对较小，但随着气候变化的加速，其影响可能会加剧。
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Risto Conte Keivabu from the Max Planck Institute for Demographic Research in Germany, the lead author of the latest paper, worked with his colleagues to calculate Spain’s total fertility rate (TFR), the average number of children a woman is expected to have over her lifetime, based on current fertility rates, for each month between 2010 and 2018.
德国马克斯·普朗克人口研究所的里斯托·康特·凯瓦布是这篇论文的第一作者，他和他的同事们共同研究了西班牙2010-2018年间每月的总生育率（TFR），即基于当前生育率，女性一生中平均生育的子女数量。

They then made use of Spanish weather data to see how the TFR varied with temperature.
随后，他们利用西班牙的天气数据，分析了TFR与温度之间的关系。

They found a clear drop in the TFR nine months after days with average temperatures between 25-30°C.
他们发现，在平均气温介于25-30°C的日子后九个月，TFR出现了明显下降。

The reduction was small but consistent, amounting to about 0.3% (equivalent to around 85 fewer babies) for each such day in a month.
这种下降幅度虽小但持续，每月每多出这样的一天，TFR就会减少约0.3%，相当于大约减少85个新生儿。

The effect increased with temperature: for each extra day above 30°C, the drop was closer to 0.8%.
而且，随着温度的升高，这种影响还会加剧：每当温度超过30°C的天数增加一天，TFR的下降幅度就会接近0.8%。
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Weather and fertility have long been linked. For one thing, human births show seasonal patterns indicating conception more regularly occurs during colder periods.
天气和生育率之间早已存在联系。首先，人类的生育具有季节性规律，表明受孕更有可能发生在较冷时期。

But this new research joins a string of recent papers reporting slumps in birth rates following spikes in daily mean temperature around the world.
然而，这项新的研究与最近发表的一系列论文一样，都报告了全球日均气温飙升后会出现生育率下降的情况。

As such heat shocks are temporary, this does not imply the hottest countries will necessarily have the lowest average birth rates.
由于这种热冲击是暂时性的，因此并不意味着最热的国家出生率就一定最低。
 
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In America over 70 years of data show that a day above roughly 27°C produces an average 0.4% drop in the birth rate (equivalent to 1,150 babies) nine months later, relative to a mild day.
在美国，长达70多年的数据显示，与温和天气相比，气温高于约27°C的一天会导致九个月后出生率平均下降0.4%，相当于减少1150个新生儿。

Other, broadly similar, effects have been reported in South Korea, Brazil and sub-Saharan Africa.
韩国、巴西和撒哈拉以南非洲也报告了类似的影响。

In March Tamas Hajdu of the HUN-REN Centre for Economic and Regional Studies in Hungary reported a Europe-wide decrease in the birth rate of 0.7% for every additional day above 25°C (see chart).
今年3月，匈牙利HUN-REN经济与区域研究中心的塔马斯·哈伊杜报告称，欧洲气温超过25°C的天数每增加一天，出生率就会下降0.7%（见图表）。

 
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What is going on? One possibility is that, as Cole Porter observed, people are disinclined to play their favourite sport when the weather is sizzling hot.
这背后的原因是什么呢？一种可能的解释是，正如科尔·波特所言，当天气酷热难耐时，人们不愿意进行他们最喜爱的运动。

This is borne out by a slight rebound across all studies in the months following a dip in either birth rate or TFR, suggesting some conception is merely postponed.
所有研究均表明，在出生率或总生育率下降后的几个月里，会出现小幅反弹，这表明部分受孕只是被推迟了。

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But the data reveal there is more to it. In 2022 Dr Hajdu published a paper with his brother, Gabor Hajdu, at the HUN-REN Centre for Social Sciences, which tracked Hungary’s conception rate as a function of weather.
但数据揭示了更多信息。2022年，哈伊杜博士与他的兄弟加博尔·哈伊杜在 HUN-REN 社会科学中心发表了一篇论文，该论文研究了匈牙利的受孕率与天气之间的关系。

Because they had access to weekly pregnancy data, rather than just the monthly birth rate, they were able to get a more fine-grained picture.
由于他们能够获取每周的怀孕数据，而不仅仅是每月的出生率，因此他们能够更细致地分析这一现象。

They found that pregnancies were not much less likely on hot days versus cool ones—the dip came around two weeks later.
他们发现，与凉爽的日子相比，热天受孕率并没有显著降低--但下降发生在大约两周后。

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That could suggest a slow-acting physiological mechanism is responsible. If so, it is likely to involve sperm.
这可能表明是一个缓慢的生理机制在起作用。如果是这样，很可能与精子有关。

Animal studies have shown pronounced but temporary drops in sperm count and quality after experimentally induced heat shocks.
动物研究表明，在实验诱导的热休克后，精子数量和质量会明显下降，但这种下降是暂时的。

Crucially, those effects emerged gradually a few weeks after the heat exposure ended.
至关重要的是，这些影响在热暴露实验结束后几周才逐渐显现。

Another study has shown similar results in humans, with heat stress leading to reduced sperm quality and mobility two to eight weeks later.
另一项研究在人类身上也显示了类似的结果，即热应激会导致精子质量和活力在2-8周后下降。

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Whatever the cause, the effect of heat on fertility rates appears to be modest, and goes on to be partly reversed.
无论原因是什么，高温对生育率的影响似乎不大，并且这种影响还会部分逆转。

For now, says Dr Keivabu, social, cultural and economic trends are more important.
凯瓦布博士说，目前而言，社会、文化和经济趋势对生育率的影响更为关键。

As global warming bites deeper, Dr Hajdu speculates, even hotter summers might heighten the effect or else prolong its impact.
哈伊杜博士推测，随着全球变暖的加剧，更酷热的夏季可能会加剧或延长这种影响。

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All this may be another argument for air-conditioning.
所有这些都可能成为支持使用空调的另一个理由。

In the American study, which included data from as far back as 1931, heat’s impact on fertility began to lessen in the 1970s as air-conditioning was more widely adopted.
在回溯至1931年的美国研究中，随着空调的日益普及，高温对生育率的影响自1970年代起开始减弱。

“Netflix and chill” may need to re-enter the lexicon.
“约剧吗？”这一说法将重新成为流行语。

（恭喜读完，本篇英语词汇696左右）
原文出自：2024年9月7日《TE》Science & technology版块

精读笔记来源于：自由英语之路
本文翻译整理: Irene
本文编辑校对: Irene
仅供个人英语学习交流使用。

【重点句子】（3个）
But global warming also has much subtler effects—including, researchers suggest, on fertility.
但全球变暖也会产生更微妙的影响--研究人员认为，其中包括对生育能力的影响。

Weather and fertility have long been linked. For one thing, human births show seasonal patterns indicating conception more regularly occurs during colder periods.
天气和生育率之间早已存在联系。首先，人类的生育具有季节性规律，表明受孕更有可能发生在较冷时期。

For now, says Dr Keivabu, social, cultural and economic trends are more important.
凯瓦布博士说，目前而言，社会、文化和经济趋势对生育率的影响更为关键。