As global temperatures continue to climb, a growing body of scientific research is sounding the alarm about the unique and often underappreciated risks extreme heat poses to pregnant people. While most are familiar with the general dangers of heat waves—think dehydration, heat stroke, or strain on the heart—few realize just how much more vulnerable pregnancy can make someone to these threats. And with climate change pushing heat records higher each year, these risks are becoming more urgent and widespread, especially for those in developing countries.
Doctors have long known that heat puts a strain on the heart, kidneys, and other organs. But for pregnant people, the challenge is even more daunting. According to the Associated Press, the body’s natural cooling processes are altered during pregnancy, making it harder to handle soaring temperatures. This isn’t just an inconvenience; it’s a problem that’s intensifying as climate change, driven largely by the burning of fossil fuels like gasoline and coal, fuels more frequent and severe extreme heat events. High temperatures that persist well into the night and shatter weather records are exposing more pregnant people to dangerous conditions than ever before.
So, what exactly makes pregnancy such a heat challenge? Anna Bershteyn, an associate professor at New York University's Grossman School of Medicine and director of Project HEATWAVE, explains: “An obvious thing is, pregnant people have a belly bump, depending how far along they are, and that’s a change in their surface to volume ratio.” In other words, as the belly grows, the heat has farther to travel to escape the body. Heat leaves your body through your skin, and when that process is disrupted, it can quickly become uncomfortable—or dangerous.
But that’s just the start. As pregnancy progresses, the body burns more calories, creating additional internal heat. The heart, already working harder to support both the pregnant person and the developing fetus, faces even more strain when the mercury rises. “The heart has to work harder, which can already be strained by extreme heat,” Bershteyn told the Associated Press. And let’s not forget hydration. Pregnant people require more fluids to stay hydrated, making them more susceptible to dehydration during hot spells, according to the Environmental Protection Agency.
There’s also a critical process at play: the body cools itself by shunting blood toward the skin and away from central organs. This is why you might notice flushed, reddened skin when you’re hot. However, for someone who’s pregnant, this can mean reduced blood flow to the placenta—the lifeline between parent and baby. Emerging research suggests that this reduced flow can affect fetal development, raising the stakes considerably.
The risks don’t stop there. Dr. Chris Holstege, chief of the division of medical toxicology at the University of Virginia School of Medicine, points out that increased blood flow during pregnancy can also increase absorption of harmful substances like pesticides. For those handling potent chemicals, extreme heat could amplify potential dangers to both parent and child.
But when does the danger begin? New studies are starting to show that exposure to extreme heat even in the months before conception may influence the outcome of a future pregnancy. Cara Schulte, a researcher with the University of California Berkeley and the nonprofit Climate Rights International, emphasizes that “research is beginning to show exposure to extreme heat even in the months before getting pregnant may affect a future pregnancy.”
During pregnancy itself, even short-term exposure to heat can increase the risk of severe maternal health complications. The EPA notes that this includes high blood pressure disorders of pregnancy, such as preeclampsia—a condition that can be fatal for both mother and child if left untreated. It’s a sobering reality that underscores just how high the stakes can be when temperatures rise.
And the mental toll shouldn’t be overlooked. Heat can worsen anxiety, depression, and feelings of isolation, all of which can be compounded during the postpartum period. Schulte told the Associated Press, “All of those things are compounded by this difficulty that postpartum women have in caring for their children in the heat.” For new parents struggling to keep their babies comfortable and safe, extreme heat can turn daily routines into exhausting ordeals.
The effects of heat exposure during pregnancy can last well beyond birth. Children exposed to extreme heat in utero may face developmental challenges throughout their lives, potentially related to adverse outcomes such as preterm birth or low birth weight. Schulte warns that these risks are not just theoretical: “As they grow up, children who are exposed to extreme heat in utero may be at increased risk of facing developmental challenges throughout their lives, potentially related to adverse outcomes such as preterm birth or low birth weight.”
Despite these mounting concerns, experts say there is still a surprising lack of research focused on women’s health and heat exposure. Bershteyn laments, “This is a hugely understudied thing,” noting that much of what scientists know about heat stress comes from studies on athletes, soldiers, or otherwise fit young people. “There hasn’t been the same level of commitment to women’s health research.”
The problem is particularly acute in developing countries, where pregnant people may face higher levels of exposure due to limited access to air conditioning, shade, or reliable healthcare. According to reporting from WRAL and the Associated Press, intensifying extreme heat events and persistently high nighttime temperatures mean more people are spending more hours each day at risk.
What’s the bottom line for those who are pregnant or planning to become pregnant? Awareness and proactive care are key. Staying hydrated, seeking shade, and avoiding strenuous activity during peak heat can help, but these are only partial solutions. The larger challenge—mitigating the effects of climate change and reducing the frequency and intensity of extreme heat events—remains a societal responsibility.
As the world continues to warm, understanding the unique vulnerabilities of pregnant people is more important than ever. The science is clear: pregnancy changes the body in ways that make heat harder to handle, and the risks are only growing. With more research, better public health guidance, and a global commitment to addressing climate change, there’s hope that future generations won’t have to face these dangers alone.
