Human activity is causing temperatures and humidity to rise, worsening air pollution, and creating smog from burning fossil fuels. Climate change is intensifying the chances of inhaling smoke from wildfires as well, and a 2026 national study found that wildfire smoke pregnancy risks now dominate the most harmful prenatal air pollution days in the U.S. All of these factors are putting pregnant women at risk. A new review of dozens of studies conducted over the past decade has revealed overwhelming evidence that negative pregnancy outcome in the US is linked with air pollution and heat exposure.
The review, published in the American Medical Association, analyzed 32 million births tracked across 68 studies, of which 84% found heat and air pollution to be risk factors. It also found 57 studies since 2007, showing a considerable connection between the two and the risk of low birth weight, pre-term birth, and stillbirth.
Bruce Bekkar, the study’s co-author, said, “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.”
According to the American College of Obstetricians and Gynecologists, climate change is an urgent threat to women’s health and a significant public health challenge. Climate change is linked with worsening respiratory disease, exposure to infectious diseases, mental health, and cardiac disease. However, pregnant women and developing fetuses are particularly vulnerable to its effects. In the investigation, 19 studies linked air pollution to preterm birth, which is when a baby is born alive before 37 weeks of pregnancy, while 25 studies linked air pollution to low birth weight and 4 to stillbirth.
Air pollution poses not only a risk for pregnant women but also anyone who is regularly surrounded by it. Emerging studies are progressively linking it to a range of health problems, including dementia. The University of California, Davis, found that traffic-related air pollution is connected to a risk for alterations in brain development that might cause neurodevelopmental disorders, such as mental retardation, dyslexia, and attention deficit hyperactivity disorder. “What we witnessed are subtle changes. But we are seeing these effects using air pollution exposures that fall within regulatory limits,” explained co-author Kelley Patten.
One of the reviewed studies on the effects of heat on pregnancy suggests that the risk of early birth increases by 11.6%, with every 5.6°C increase. Bekkar hopes medical practitioners will not only educate patients about climate change but also share the review’s findings with their patients and advise them to avoid long exposures to heat and pollution.
