Research press release


Nature Climate Change

Climate Change: Hot temperatures and early childbirth



今回、Alan BarrecaとJessamyn Schallerは、米国内の郡レベルの1日の出生率の推定変動率を用いて、20年間にわたる高温気象に関連した妊娠期間の短縮日数の総数を定量化した。今回の研究で用いられたサンプルには、300万郡・日以上にわたる5600万人の出産が含まれていた。論文著者は、最高気温が摂氏32.2度(華氏90度)を超える日に出生率が5%上昇し、平均妊娠期間が6.1日短縮すると推定している。一部の出産は、2週間の早産だった。


An average of 25,000 infants per year were born earlier as a result of hot weather, with a loss of more than 150,000 gestational days annually in the United States from 1969 to 1988, suggests a paper published in Nature Climate Change. Hot weather can cause an increase in deliveries on the day of exposure, with births occurring up two weeks early.

Increased exposure to hot weather due to climate change is likely to harm infant health, though the scale of this threat has not been well documented. Shorter gestational periods have been linked to negative health and cognitive outcomes later in life. Previous research suggests that hot weather leads to an acceleration of childbirth and shorter gestations. However, it is unknown exactly how many days of gestation are lost due to hot weather.

Alan Barreca and Jessamyn Schaller used estimated shifts in daily birth rates from counties across the United States to quantify the total number of lost days of gestation associated with heat over a span of 20 years. The authors’ sample included 56 million births spanning more than 3 million county-days. They estimate that birth rates increase by five percent on days with a maximum temperature above 90°F (32.2°C), with an average gestational reduction of 6.1 days. Some births occurred two weeks early.

The authors conclude that, according to climate projections, an additional 250,000 gestational days could be lost annually by the end of the century.

doi: 10.1038/s41558-019-0632-4


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