• Air pollution and heat exposure linked to negative outcomes
  • Researchers discover ‘pretty scary health burdens’

More than a decade of overwhelming evidence links air pollution and heat exposure with negative pregnancy outcomes in the US, according to a new review of dozens of studies.

The investigation, published in the Journal of the American Medical Association, identified 57 studies since 2007 showing a significant association between the two factors and the risk of pre-term birth, low birth weight and stillbirth.

Black mothers were particularly at risk, as were people with asthma.

The review analyzed 32m births tracked across 68 studies. Of those, 84% found air pollution and heat to be risk factors.

Human-caused climate disturbances are forcing temperatures higher, raising humidity and reducing people’s ability to cool off even at night. Climate change also makes air pollution worse. Smog from the burning of fossil fuels forms on hot days. And wildfires that cause smoke inhalation are exacerbated by the crisis.

“When you talk about climate, people think about severe weather, big storms or huge fires … but we wanted to talk about the impacts that are common and widespread and ongoing and also are rarely attributed to the climate crisis,” said Bruce Bekkar, a co-author of the study and a retired obstetrician.

Pregnant women on a climate march in Sydney in December last year. Researchers found a strong link between air pollution and heat exposure and the risk of pre-term birth or stillbirth. Photograph: Jenny Evans/Getty Images

“We are already having generations weakened from birth. There’s just no way we can allow that to happen, and I would like to see not just mothers and their husbands and kids show up at council meetings, but I’d like to see many more health professionals involved in calling for legislation that reduces the ongoing and really pretty scary health burdens of the climate crisis.”

The findings come as the Trump administration has sought to weaken pollution protections and climate efforts, including by rolling back standards for car and power plant emissions. Trump’s Environmental Protection Agency has also ignored scientists’ advice to enact stricter air quality rules.