Doctors and scientists have long understood that heat places considerable strain on the human body, particularly the heart, kidneys, and other vital organs. Yet, for those who are pregnant, this risk is even greater. Their bodies, already undergoing significant change, must work overtime to regulate temperature — and as the world’s climate grows hotter due to the relentless burning of fossil fuels like gasoline and coal, the challenges for pregnant people are multiplying.
Climate change is not just a distant threat; it is here, now, intensifying extreme heat events, pushing temperatures up even through the night, and shattering weather records across the globe. According to reporting from MedPage Today and the Associated Press, this means more frequent and prolonged exposure to dangerous heat for pregnant people, especially in developing countries where resources to cope with such extremes are often limited.
But what exactly makes pregnancy so much more challenging during heat waves? Anna Bershteyn, an associate professor at New York University’s Grossman School of Medicine and director of Project HEATWAVE, explains that the physical changes of pregnancy play a key role. “An obvious thing is, pregnant people have a belly bump, depending on how far along they are, and that’s a change in their surface-to-volume ratio,” Bershteyn told MedPage Today. This seemingly simple anatomical shift actually makes it harder for the body to shed heat. Since heat dissipates through the skin, a larger belly means heat has farther to travel before it escapes.
As pregnancy advances, the body becomes a veritable furnace, burning more calories and generating more internal heat. The heart, already working harder to support both parent and fetus, can be further strained by high temperatures. The Environmental Protection Agency (EPA) notes that hydration needs also increase during pregnancy, making dehydration a much more common — and dangerous — risk when the mercury climbs.
One of the body’s primary cooling mechanisms is to shunt blood toward the skin and away from central organs. This is why people often flush and turn red when overheated. However, emerging research indicates that this process may reduce blood flow to the placenta, potentially affecting fetal development. For those who work with potent substances like pesticides, the risk is even greater. Dr. Chris Holstege, chief of the division of medical toxicology at the University of Virginia School of Medicine, highlighted that increased blood flow during pregnancy can also increase chemical absorption, posing additional threats to both parent and unborn child.
The risks associated with extreme heat aren’t limited to the pregnancy itself. Cara Schulte, a researcher at the University of California Berkeley and with the nonprofit Climate Rights International, pointed out that exposure to extreme heat even in the months before conception can impact a future pregnancy. “Research is beginning to show that exposure to extreme heat, even in the months before getting pregnant, may affect a future pregnancy,” Schulte told the Associated Press.
During pregnancy, even short-term exposure to high temperatures can significantly increase the risk of severe maternal health complications. The EPA specifically cites high blood pressure disorders of pregnancy as a major concern, including preeclampsia — a condition that can be fatal for both parent and child if not managed promptly and effectively.
But the dangers of heat exposure extend beyond the physical. Heat can worsen existing mental health challenges such as anxiety and depression, and can intensify feelings of isolation. Schulte notes that after the baby is born, “all of those things are compounded by this difficulty that postpartum women have in caring for their children in the heat.” Trying to soothe a crying infant or breastfeed in a sweltering room is taxing under the best of circumstances; add in the relentless heat and it can become nearly unbearable.
Perhaps most concerning is the growing body of evidence that children exposed to extreme heat in utero may face increased risks of developmental challenges throughout their lives. These challenges may be related to adverse outcomes such as preterm birth or low birth weight, which can set the stage for a host of health and developmental issues later on. Schulte’s research underscores that the full scope of these risks is only beginning to be understood.
Despite the mounting evidence, Bershteyn laments that this area of research remains “hugely understudied.” She points out that much of what scientists know about heat stress comes from studies involving athletes, soldiers, or otherwise fit young people. “There hasn’t been the same level of commitment to women’s health research,” she told MedPage Today. This gap in knowledge is particularly troubling given the unique physiological demands of pregnancy and the growing threat posed by climate change.
All of this comes at a time when heat waves are becoming more frequent, intense, and prolonged around the world. According to the Associated Press, these trends are largely driven by human activity, especially the burning of fossil fuels. As a result, pregnant people are finding themselves on the front lines of a public health crisis that is only expected to worsen in the coming years.
In developing countries, the risks are even more acute. Limited access to air conditioning, clean water, and healthcare means that pregnant people in these regions are often exposed to the worst effects of extreme heat with little means of protection. The EPA and other health agencies are sounding the alarm, calling for more research, better public health messaging, and increased support for vulnerable populations.
What can be done in the meantime? Experts recommend that pregnant people pay close attention to hydration, seek shade or air conditioning whenever possible, and avoid strenuous activity during the hottest parts of the day. Healthcare providers are also encouraged to monitor their pregnant patients more closely during heat waves and to educate them about the signs of heat exhaustion and dehydration.
Still, as Bershteyn and others point out, these are only stopgap measures. Without a sustained commitment to reducing greenhouse gas emissions and adapting public health strategies to a hotter world, the risks for pregnant people — and their children — will only continue to grow.
The science is clear: pregnancy makes it harder for the body to handle heat, and climate change is making heat harder to escape. As the world warms, the health of pregnant people and the next generation is increasingly at stake. Addressing this challenge will require not just individual vigilance, but collective action and a renewed focus on women’s health research.
For now, the message from doctors and scientists is straightforward: extreme heat is not just uncomfortable — for pregnant people, it can be downright dangerous. As climate change accelerates, understanding and addressing these risks has never been more urgent.
