PARIS, May 14, 2025 (BSS/AFP) - Scorching heatwaves fuelled by global warming are increasing the risk of dangerous complications during pregnancies across the world, a report warned on Wednesday.

Being exposed to extreme heat while pregnant has previously been linked to a range of problems, including a higher risk of premature birth, stillbirth, birth defects and gestational diabetes.

The new report from the US-based research group Climate Central sought to measure how much more pregnant women have been exposed to excessive heat since 2020 -- and to what extent climate change is to blame.

In 222 out of the 247 countries and territories studied, "climate change at least doubled the average annual number of pregnancy heat-risk days experienced during the past five years", the report said. 

The biggest increases were in developing countries where access to healthcare is limited, such as in the Caribbean, Central and South America, the Pacific islands, Southeast Asia and sub-Saharan Africa.

The researchers only looked at the rise in potentially dangerous hot days and did not examine the extent to which pregnant women were actually affected by heat in the countries.

Ana Bonell, a maternal health and extreme heat researcher at London School of Hygiene and Tropical Medicine not involved in the report, said it "gives clear evidence of the growing exposure risk to extreme heat".

The findings could also apply to the elderly, another group who are more at risk during blisteringly hot periods, she told AFP.

While researchers are increasingly documenting the many ways that extreme heat can threaten human health, there remain "many unknowns" about the physiological mechanisms to explain why this happens, Bonell said.

A large 2024 study in Nature Medicine estimated that heatwaves increase the odds of having a complication during pregnancy by 1.25 times.

Beyond wider efforts to fight climate change -- which is largely caused by humans burning fossil fuels -- experts advised local policies to help communities beat the heat.

These include "greening neighbourhoods, limiting pollution, creating cool areas and informing residents about the risks," French epidemiologist Lucie Adelaide said.

In a statement linked to the new report, she also recommended that existing information about the health risks of heatwaves include warnings for pregnant women, who are currently rarely mentioned in such efforts.