"A forgotten population": Researchers work to ensure pregnant people and reproductive health aren't left behind amid wildfire smoke concerns

As wildfires in North America and Europe spark concerns for those especially sensitive to air pollution, some researchers want to ensure that pregnant people aren't overlooked.

"I think they're often a forgotten population when it comes to air pollution in general," said Amy Padula, a professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the University of California, San Francisco, and the Acting Director of the Program on Reproductive Health and the Environment. 

"I think people think heart attacks, people think asthma. But they don't think about pregnant people."

That may be true at a public communications level, with air pollution alerts often highlighting health risks for children, older adults, and those with heart or lung disease. But researchers are exploring a range of ways in which exposure to wildfire smoke may affect fertility, pregnant people, and pregnancy outcomes.

Some reporters have even gone so far as to suggest delaying in vitro fertilization, or IVF, treatments over concerns that poor air quality could impact embryo development and transfers. 

Studies published in 2022 and 2026 have associated wildfire smoke exposure with lower yields of blastocysts — early-stage embryos — and a potential for reduced success in embryo transfer and pregnancy. However, Padula, who is currently involved in separate studies exploring the effects of wildfires on sperm quality and IVF outcomes, doesn't think fertility treatments should necessarily be delayed due to poor air quality.

"I would not recommend a blanket rule that every IVF patient should delay treatment during a wildfire," Padula told CG. "The evidence is still limited and somewhat mixed," she continued, underscoring a need for more research and noting that previous studies have addressed risks at the population level.

"What's important to think about on an individual level is … how urgent is the treatment? Is this an incredibly stressful time for our family because of weather evacuations or just changes in their daily lives because of the wildfires or the smoke? And to what extent can one protect themselves, stay indoors, have air filtration systems, and feel like they're not suffering from the smoke?"

In addition to emphasizing that studies on IVF and wildfires have not yet provided definitive recommendations regarding the timing of their treatment, Padula pointed out that pre-conception and prenatal smoke exposure could possibly impact fertility care at several different points, from egg and sperm collection to embryo development, embryo transfer, and pregnancy itself. That is, findings haven't pointed to just one portion of the treatment course when smoke exposure could be the most damaging, making it difficult to avoid exposure through rescheduling alone. 

"Every cycle there's something going on in the world," Padula said, so it can be hard to sidestep all potentially adverse circumstances. Still, reducing exposure to wildfire smoke and to air pollution in general is always a good idea for human health and especially so for pregnant people.

This may be because pregnant people inhale more air, because their hearts are working harder, because of the significant physiological stress of growing a fetus. Researchers aren't yet entirely sure, but they have been working to identify a range of potential pregnancy-related risks associated with wildfire smoke exposure, from low birth weight to high birth weight, problems with placental function, and more.

Meanwhile, Padula indicated that chief among the concerns is preterm birth.

"The strongest evidence that we see with wildfire smoke — and that's been consistent across studies, across locations, across all the different kinds of methods of quantifying smoke — is preterm birth," she said.

Padula also told CG that serious maternal health issues potentially linked to smoke exposure — such as preeclampsia and other hypertensive disorders — "may be kind of on that causal pathway to preterm birth."

"We have also found associations with severe maternal morbidity," Padula said, pointing to a study that she co-authored and published last month. "These are really extreme and dangerous outcomes for mothers during pregnancy, and we found [them] associated with really high levels of exposure to wildfire smoke."

Her team's findings emphasize that wildfire-complicated pregnancies can be dangerous not only for fetuses but also for mothers. This may be especially true as related to smoke exposure in the second and third trimester and for those from Black and Asian and Pacific Islander communities who already experience unequal access to high-quality maternal health care.

When it comes to sharing details about the risks of smoke exposure, Padula said she thinks there can be some hesitation over concerns that awareness may stress pregnant people already flooded with do's and don'ts guiding prenatal behavior. "But I also feel like that can feel a little sexist or kind of anti-feminist," she said, underlining the importance of spreading evidence-backed knowledge about hazards and preventative measures as credible evidence emerges.

So what can individuals, communities, and governments do to mitigate the hazards? 

In the big picture, taking steps to reduce the human-caused pollution that has induced climate change and, consequently, is exacerbating wildfires will continue to be critical. There are also forest management practices to help reduce wildfire risks. And funding scientific research at the intersection of climate, environment, and reproductive health could offer new insights about possible complications and how to address them.

In the meantime, individuals, grassroot groups, and officials can coordinate to improve access to information, tools, and policies to protect pregnant people — and people concerned about their reproductive health — from the dangers of wildfire smoke. 

Experts recommend reducing time outdoors in areas affected by air quality warnings and, when indoors in those areas, keeping doors and windows closed. 

If and when you have to be outdoors, wearing a properly-fitted N95 mask can reduce exposure to smoke and to air pollution more generally, including the industrial and traffic-related pollution that can disproportionately impact low-income communities and communities of color. 

The use of HEPA filters (or DIY air filters) can be effective depending on how tightly sealed an indoor space is. Padula suggested that municipalities improve equitable access to such filtration by launching clean air centers — similar to the cooling centers vital to public health amid heat waves. In fact, if carefully designed to allow for cool air circulation while preventing smoke infiltration, these facilities could be one in the same.

Padula stressed that worker protections are also essential, especially for those who work outdoors. 

"What can we do to protect workers so that they're not being exposed for long periods of time?" she posed, pointing to community-centered research focused on farmworkers, many of whom are immigrants or living in low-income rural areas and meanwhile doing the critical work of supporting major industries and whole food systems for huge numbers of people. "This is a population that's of particular interest."

Policies that provide options to work remotely, to work indoors temporarily, to take paid time off, ensure job security, and ensure access to protective equipment as well as affordable medical care could help. 

Padula underlined that any interventions, though, must be implemented with community input to make sure they are culturally acceptable and meet real needs, which is part of her current work. 

She is also involved in further research looking at "wildfire smoke in relation to semen quality and also IVF outcomes." 

A separate study based at Colorado State University has been exploring the effects of smoke exposure on male reproductive health among wildland firefighters.

Recalling her emphasis on worker protections for those exposed to wildfire smoke, Padula noted, "Firefighters are another population that we're very concerned about on many levels — both the smoke and then also all the chemicals that come with firefighting."

The observation highlights a major consideration at the nexus of climate, environment, and reproductive health research — so much of it requires investigation into multiple and compounding factors. Among those overlapping hazards are, sometimes, extreme heat, drought, and wildfires, since communities may be exposed to all at once, or, in a causal chain, one after the other.

"In some cases, we're concerned with wildfire smoke and heat together because they often co-occur," Padula said. "That might not be the case always, but this may be something that makes sense to attack together."

"If we can solve two problems at once, it would be ideal."

Kirsten Krueger contributed to the editing of this article.