Extreme heat could make pregnancy riskier for millions of women: Report

(WEST PALM BEACH, FL) — As human-induced climate change continues warming the planet, pregnancy risks are increasing, according to a new analysis by Climate Central.

Climate Central, a nonprofit science and communications organization, analyzed daily temperature data from 2020 to 2024 in 940 cities across 247 counties and territories. Researchers looked for “extreme heat days,” which are defined by temperatures that go beyond what’s normal in the area 95% of the time.

The high temperatures are associated with an increased risk of preterm birth and threats to maternal health; therefore, Climate Central has coined the phrase “pregnancy heat-risk days.”

Over the last four years, nearly one-third of the countries that Climate Central surveyed experienced at least one additional month of pregnancy heat-risk days on average, according to the new report.

For most of those countries, the pregnancy heat-risk days doubled — a pattern that can be linked to climate change, researchers showed.

“Even a single day of extreme heat can raise the risk of serious pregnancy complications,” said Climate Central’s vice president of science, Kristina Dahl, in a statement. “Climate change is increasing extreme heat and stacking the odds against healthy pregnancies worldwide, especially in places where care is already hard to access.”

Extreme heat can increase the risks of pregnancy complications and is linked to high blood pressure, diabetes, hospitalizations, premature births or even death, according to major health organizations such as the World Health Organization and the Centers for Disease Control and Prevention.

The United States has experienced an increase of 12 pregnancy heat-risk days each year on average.

The analysis found that West Palm Beach, Florida, experienced the most significant increase in pregnancy heat-risk days in the U.S. — jumping 48% between 2020 and 2024. Going by state, Utah saw the biggest increase, with 23 additional days, a 72% increase since 2020.

The analysis also found that all of Hawaii’s pregnancy heat-risk days can be attributed to climate change. In other words, pregnant people living in Hawaii would never have been subjected to the risk of extreme heat if not for the changing climate.

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

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

After West Palm Beach, the cities rounding out the five hardest-hit in nation’s states and territories are: Miami, Florida; San Juan, Puerto Rico; Odessa, Texas; and Salt Lake City, Utah.

After Utah, the hardest-hit states are: Colorado, New Mexico, Arizona and Hawaii.

The analysis by Climate Central has not been peer-reviewed, and it does not differentiate between different types of pregnancy complications.