Rising heatwaves putting pregnancies at risk

In a sobering reminder of how global warming is reshaping human health, a new study has found that climate change has doubled the number of dangerously hot days for pregnant people in nearly 90 per cent of countries and territories around the world.

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The analysis, conducted by Climate Central, directly quantifies how rising temperatures — largely driven by the burning of fossil fuels — are increasing the risk of heat exposure during pregnancy. Using temperature data from 2020 to 2024 across 247 countries and 940 cities, researchers calculated the rise in what they term pregnancy heat-risk days — days when maximum temperatures exceed 95 per cent of historical local records. These days are linked to increased rates of preterm birth, hypertension, gestational diabetes, and other complications.

“Extreme heat is now one of the most pressing threats to pregnant people worldwide,” said Dr Bruce Bekkar, a women’s health physician and an expert on climate-related health risks. “It’s pushing more pregnancies into high-risk territory, especially in places already struggling with limited healthcare access.”

According to the report, climate change added at least 30 additional heat-risk days each year in nearly one-third of countries. In some of the most severely affected areas — including parts of the Caribbean, Central and South America, Southeast Asia, the Pacific Islands, and sub-Saharan Africa — all of the extreme heat days experienced over the past five years were attributed to human-caused climate change.

The consequences are particularly dire in regions with fragile healthcare systems.

“Climate change is increasing extreme heat and stacking the odds against healthy pregnancies worldwide,” said Dr Kristina Dahl, vice president for science at Climate Central. “Even a single day of extreme heat can raise the risk of serious pregnancy complications.”

The study used two core methods to assess the risk. First, it counted days where temperatures exceeded the 95th percentile of historic local ranges — a threshold known to elevate the risk of preterm birth. Second, it employed Climate Central’s Climate Shift Index, which compares real-world temperatures to a model of a planet unaffected by human-driven warming. This allowed researchers to estimate how many heat-risk days were directly caused by climate change.

Every country studied saw an increase in such days. In 222 out of 247 countries and territories, climate change had at least doubled the annual number of pregnancy heat-risk days. The scale of the increase highlights the inequitable burden of climate impacts: developing nations, which have contributed the least to global greenhouse gas emissions, are often the hardest hit.

Medical experts warn that these findings signal a growing public health emergency.

“Cutting fossil fuel emissions isn’t just good for the planet,” Bekkar emphasised. “It’s a crucial step toward protecting pregnant people and newborns around the world.”