The Risks of Wildfire Smoke Exposure During Pregnancy Are Becoming Clearer

The sky was black as Roshny B. Martuscelli hurried from the driveway into the house, her 2-year-old and 8-month-old children in tow. The flames of several wildfires were burning miles away from their Oregon home, yet the smoke brought immediate danger — something she urgently shielded her children and their developing lungs from.

It was 2020, and they had just returned home from a long road trip from Arizona to see family, where they watched fires burn from the interstate highway. As ash surrounded them, she was grateful they already had their masks on.

Two summers later, she found herself in a similar situation, when soot drifted from the forest and fell like snow against a smoky backdrop. This time she was trying to protect not only both her children but also their unborn sibling. Nine months pregnant and living with asthma, she had to be cautious about her exposure. 

“I almost felt like I was catching my breath every time I would go outside; it was suffocating at times,” said Martuscelli. “It very much feels like a bird in the cage situation; we can look outside, but we can’t go out there.” 

Since the start of this decade, dozens of U.S. cities in Western states, from the Rocky Mountains to the Pacific Coast, have experienced spikes in tiny, harmful particles in the air, averaging nearly 20 unhealthy days of heavily polluted air annually. Trends show that wildfires have consistently been a significant contributor to what the American Lung Association calls short-term particle pollution, referring to surges in particulate matter that can last from hours to days. 

In its 2024 report, the association estimates that 711,081 pregnant people across the country have recently lived in areas with a failing grade for short-term particulate matter exposure. This is a vulnerable population that undergoes physiological changes throughout the body, including an increased respiratory rate that means taking in more breaths per minute than someone who isn’t pregnant. 

Compared to air pollution from other sources, such as cars or power plants, wildfire smoke can be particularly dangerous to human health, because the small particles it contains vary depending on what is burning — ranging from pollen to heavy metals. Even healthy people exposed to wildfire smoke can experience symptoms including coughing, headaches and fatigue. That’s because these tiny particles can be inhaled deeply into the lungs, where they then enter the bloodstream and travel throughout the body and into various organs.

But pregnant people are at greater risk, because their cardiac output can be up to 50% higher. Poor air quality — as ranked in the U.S. on an Air Quality Index that measures air from good to hazardous — has been linked to an increased risk of miscarriage, preterm birth, high blood pressure and more. 

Emerging research on wildfire smoke and pregnancy highlights disproportionate risks at every stage, from preconception to birth outcome. Now scientists, some of whom were themselves pregnant or trying to conceive while fires raged, are warning that pregnant people in many parts of the country face an increasingly smoky future, with few realistic means of protecting themselves. 

Molly Kornfield was pregnant during one of the nation’s most intense wildfire seasons on record. In 2020, people in California, Oregon and the state of Washington experienced as many as 100 days of unhealthy air from fires that burned hot and extensively across the coast. 

Kornfield was worried about more than her own safety; as a fertility doctor at Oregon Health and Science University, she felt concern for her dozens of patients. Yet little data existed on how this sudden and severe pollution could affect people seeking treatment in her in vitro fertilization (IVF) lab. 

“My own reproduction got me really interested in this question, and I anticipated that some of my patients would have a lot of the same questions about what to do in that kind of event,” she said. 

Kornfield and her research team conducted a study of the 69 patients who underwent ovarian stimulation and IVF treatment during the six weeks leading up to and during the catastrophic smoke event. They found that wildfire smoke exposure was linked to a lower number of viable blastocysts, the early stages of a fertilized egg that are deemed fit to be transferred into the womb. 

While most IVF cycles in Kornfield’s cohort still had strong outcomes, meaning a higher number of viable blastocysts for a potential pregnancy, the findings are leading her to recommend that providers consider delaying starting IVF or transferring embryos for patients at high risk of smoke exposure. Although her research is preliminary, she believes that expanding environmental studies on reproductive impacts is imperative — and she’s not alone. 

With an average of 73,000 wildfires now igniting in the U.S. each year, according to the U.S. Forest Service, dozens of public health researchers have shifted their focus to the severe air pollution these fires create. 

“We’ve really just started to look at wildfire smoke exposure,” said Rupa Basu, the head of air and climate epidemiology within the California Environmental Protection Agency. “I grew up in California, been here all my life, and it has not been an issue until just a few years ago.” 

For more than 20 years, Basu has studied the impact of rising temperatures. When she was in her second pregnancy during the hot summer of 2007, she felt uncomfortably warm and couldn’t find information on how it might affect pregnancy complications or early birth. Babies born before 37 weeks face a higher risk of developmental delays and long-term health issues. 

She gathered data that led to a groundbreaking study on preterm births and heat exposure. That’s when she found out that the highest risk groups were would-be parents with asthma and people of color, particularly Black mothers, who were up to 2.5 times more likely to experience preterm births compared to white women. 

“There’s already a disparity, just where people live,” said Basu, referring to decades of segregation and racist policies that have left Black women living in areas more likely to have air pollution and natural disasters. 

As peer-reviewed reproductive health research advances, data continues to reveal disproportionate exposure to environmental hazards, such as living near industrial zones. This year, a University of California, Berkeley analysis of particulate matter from California wildfires found that Native American populations consistently faced elevated exposure, with socioeconomic factors potentially amplifying their disparities. Amy Padula, an author of the study and researcher at the University of California San Francisco School of Medicine, emphasized that addressing inequity and exposure requires examining the issue through the lens of race and ethnicity. 

“Sometimes Native Americans get lumped in with ‘other,'” said Padula, explaining that groups are often not categorized with care in data reporting. “But when we start to separate different groups, we see much more vulnerability in specific areas.”

In California, up to 4% of preterm births have been linked to wildfire smoke. Padula also led a study this year that found that wildfire smoke exposure, no matter what week of pregnancy it occurs in, is associated with an increased risk of preterm births. The study analyzed data from 5.6 million births over 10 years in California. Researchers examined pregnancies week by week, finding some indication that those in their second and third trimesters were more vulnerable, though no specific period of heightened sensitivity was identified. 

In her research, Padula and her colleagues have called for strategies that support equitable health interventions to reduce exposure. Currently, common safety advice revolves around staying indoors, limiting outdoor activities and using high-quality air filters. 

But she knows from her work and lived experience that housing is a fragile buffer. In 2018, during the disastrous Camp Fire, one of the deadliest and most destructive wildfires in California’s history, Padula was pregnant. Smoky air found a way into her home and her toddler started coughing. 

“More than I could feel scared for myself or for my unborn baby at the time, I was more concerned about her, because every morning she’d wake up and sounded like Darth Vader,” said Padula. “Even with all the resources and knowledge, it’s just not enough to protect yourself.”

Those living in leaky, aging homes without air conditioning receive little protection from the government, and medical advice to stay indoors and shut windows — a reality all too common in the Western U.S. — is of little benefit. 

But the struggle to find affordable and adequate housing is so severe that low-income Hispanic and Black individuals are disproportionately pushed out of urban centers and closer to the epicenters of wildfires and to denser smoke. These are areas where people with more means choose not to live. 

A 2024 report from Human Rights Watch on reproductive rights and wildfires found that in Oregon, which faces one of the highest rates of houselessness and the lowest availability of affordable rental properties in the country, a community doula program has observed that nearly 25% of the people they care for are insecurely housed. Wildfires are making housing instability worse, especially when it comes to long-term displacement, as experienced by Sarah Johnson in Montana. 

In 2017, during the Lolo Peak Wildfire, when over 78 square miles of two national forests were burned, flames crested the mountain near her family farm and house, forcing her to evacuate at midnight to escape the smoke. She was in her third trimester.

Johnson still went to work as a bedside nurse. The sister of one of her co-workers opened her living room to Johnson as a makeshift home, where she stayed for weeks with little guidance on how to protect herself. Even as a health care professional, she often reflects on how unprepared she was to cope with the lingering smoke. 

“I’ve realized how little information I received about the impacts of wildfire smoke on me or my baby,” said Johnson. “The smoke index, the air quality index. I didn’t know what that was. I didn’t know how to read it.” 

Local agencies issue alerts for fires but not for smoke. Residents turn to resources like AirNow.gov, the public source for real-time updates on this index: a scale from 0 to 500, where higher numbers indicate worse air quality. The website has made efforts to present the information in an accessible way, with dark red indicating hazardous conditions. The expectation that individuals interpret air quality data can play into unequal exposure, however, especially among non-English speakers who may struggle to fully understand the website, making it harder for them to take protective measures.

Even those who have the information are left with tough choices about whether to stay inside. For many, it could mean missing a paycheck or facing penalties from employers, according to the Human Rights Watch report, which was informed by more than 50 health care and birthing practitioners. For those in low-income immigrant communities, especially farm workers, their bodies are never able to escape the constant exposure to smoke.

“These workers, they’re still expected to go outside and pick the fruit, or tend to whatever they need to do, while there are wildfires in that area, and while the smoke is heavy and significant,” said Hilda Berganza, climate manager for Hispanic Access Foundation. “It leads to a whole other conversation about workers’ compensation.” 

Seventy-eight percent of all farmworkers in the U.S. identify as Hispanic, according to the Department of Labor. For decades, they have been devalued, denied access to overtime and excluded from minimum wage protections. 

Berganza points out the need to designate a block of days each year for extreme weather, ensuring workers are compensated regardless. A socioeconomic study last year found that barriers to health care for farmworkers often stem from cost and, in California, this is compounded by the distance to care. Even those with access to health care may not receive the same quality of care, depending on their insurance and providers. This is a widespread issue for mothers across the U.S., particularly Black women. 

In the nation’s maternal mortality crisis, Black women face a rate of 44 deaths per 100,000 live births, compared to 17.9 deaths among white women. Implicit bias is a factor recognized by U.S. agencies. Health care providers are less likely to recognize pain in Black patients, leading to disbelief about the severity of their discomfort, according to the National Institutes of Health. Similar discrimination also plays into unacceptable disparities that Native American and Alaska Native women face during their pregnancies. 

The question of who bears the greatest burden in terms of reproductive rights has become a central topic in American politics, especially with the 2024 presidential election — the first since the overturning of Roe v. Wade. The Supreme Court’s Dobbs decision, influenced by judges appointed during Donald Trump’s first administration, shifted the legal landscape, leaving reproductive rights to be decided on a state-by-state basis. 

On the campaign trail, Vice President Kamala Harris pledged to restore the protections of Roe v. Wade, while President-elect Trump avoided questions about a potential national abortion ban. For the nation, it’s a wait-and-see situation, not only for policies regarding reproductive health but also the climate. 

Scholars who study equitable solutions at the intersection of environmental and reproductive health underscore that solutions lie in reimagining systems to address these overlapping issues.

“Climate change has been part of reproductive justice since its inception,” said Dr. Monica McLemore — an expert in anti-racist birth equity based at the University of Washington — referring to the reproductive justice movement created by a group of Black women 30 years ago this summer. 

Researchers in climate adaptation and reproductive health, like McLemore, are working tirelessly to develop concrete strategies to protect pregnant people from smoke waves. Progress is slow, however, as they navigate laws that restrict bodily autonomy and limit access to health care, which in turn perpetuates deep-rooted and systemic inequities based on race, occupation and socioeconomic status. 

Reproductive justice, as outlined in the academic literature, extends beyond choice to emphasize access. It addresses intersectional climate change issues by aligning long-term goals with actionable short-term solutions, which McLemore calls “retrofits” — tangible public services that meet urgent needs while paving the way for deeper structural change. 

Yet many, like Martuscelli, aren’t living in a place with proactive, justice-informed policies. While the American West has faced extreme wildfires and their smoke for years, the issue is only now gaining broader attention across the country as fumes begin to impact major East Coast cities like New York.

“As Oregonians and people that live in Oregon, we have always been mindful of the smoke, our surroundings and our environment. I just wish other people took it as seriously as we do,” she said. “It always feels like an afterthought when these things happen.”

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