Extreme heat risks to pregnancy driven by climate change: Japan
2020 to 2024
We counted the number of days with temperatures warmer than 95% of temperatures observed at a given location (also referred to as temperatures above the 95th percentile) — a threshold which research1 shows can bring increased risk of preterm birth. We define these extremely hot days as “pregnancy heat-risk days.”
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During the past five years, Japan experienced an average of 15 additional pregnancy heat-risk days each year.
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Climate change accounted for 45% of the average annual number of pregnancy heat-risk days in Japan during 2020 to 2024 (adding 15 of 33 days), compared to a world without climate change.
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In the city of Osaka, climate change accounted for 70% of the average annual number of pregnancy heat-risk days (23 out of 33) during 2020 to 2024.
Explore data for prefectures and cities across Japan in the interactive maps below.
Prefectures with the most pregnancy heat-risk days added by climate change
Cities with the most pregnancy heat-risk days added by climate change
1We chose this percentile based on peer-reviewed research from Kuehn et al. (2017), Wang et al. (2013), Wang et al. (2024), and McElroy et al. (2022).