PARIS – Extreme heat driven by global warming is putting millions of pregnant women at increased risk of dangerous complications, according to a new report released Wednesday by U.S.-based research group Climate Central.
Exposure to excessive heat during pregnancy has long been linked to a higher risk of premature birth, stillbirth, birth defects, and gestational diabetes. The latest study now quantifies just how much climate change has intensified this threat in recent years.
Analyzing data from 247 countries and territories, the report found that in 222 of them, climate change has at least doubled the average annual number of “pregnancy heat-risk days” over the past five years.
The steepest increases were seen in developing countries—particularly across the Caribbean, Central and South America, the Pacific Islands, Southeast Asia, and sub-Saharan Africa—regions where access to quality maternal healthcare is often limited.
While the study focused on the growing number of dangerously hot days, it did not assess how many pregnant women were directly harmed by the heat in each country.
Ana Bonell, a maternal health and climate expert at the London School of Hygiene and Tropical Medicine, who was not involved in the study, said the findings offer “clear evidence of the growing exposure risk to extreme heat,” adding that similar risks likely apply to other vulnerable groups such as the elderly.
Despite growing documentation of how extreme heat harms human health, Bonell noted that researchers still don’t fully understand the biological mechanisms that make pregnant individuals more vulnerable.
A separate study published in Nature Medicine in 2024 found that heatwaves increase the risk of pregnancy complications by 25%.
Beyond tackling the root cause of climate change—mainly the burning of fossil fuels—experts are urging local action to help protect at-risk communities. Recommended strategies include planting more greenery, reducing air pollution, building cool public spaces, and educating residents on heat-related health risks.
French epidemiologist Lucie Adelaide emphasized the need for public health campaigns to include targeted warnings for pregnant women, who are often overlooked in current heatwave safety messaging.
