The Impact of Wildfire Smoke on Pregnancy Outcomes

by yaleglobalhealthreview, posted in Uncategorized

BY MICHELLE CHEON

Rising global temperatures and their contribution to prolonged droughts have led to an increase in both the frequency and intensity of wildfires. This escalation has profound consequences on air quality, exposing millions of individuals to hazardous smoke. Among the most vulnerable populations to decreasing air quality are pregnant individuals, for whom wildfire smoke exposure poses unique risks to themselves and their pregnancy outcomes. Wildfire smoke is composed of a mixture of pollutants, including fine particulate matter (PM2.5) polycyclic aromatic hydrocarbons (PAH), and carbon monoxide, many of which are miniscule enough to cross the placental barrier and affect fetal development. Understanding the risks of such chemical exposure is critical for developing targeted public health interventions to protect maternal and fetal health. 

Biological Effects

Smoke exposure disrupts maternal respiratory and cardiovascular systems, compromising oxygen and nutrient delivery to the fetus. Among the variety of pollutants in wildfire smoke, PM2.5 is particularly concerning due to its micron level size, which allows it to penetrate deep into the lungs, enter the bloodstream, and reach the placenta. Once inhaled, PM2.5 generates reactive oxygen species, which are highly unstable oxygen-based molecules that readily react with cellular components causing oxidative stress, inflammation, and widespread cellular damage. Carbon monoxide further compounds these risks by binding to hemoglobin with a far greater affinity than oxygen, inducing maternal and fetal hypoxia. PAHs, another major component of wildfire smoke, are known for their carcinogenic properties, crossing the placental barrier and interfering with fetal growth and organ development [1]. 

As systemic inflammation and vascular stress increase, pregnancy-related complications such as hypertension, preeclampsia, and gestational diabetes become more likely; however, one of the most concerning outcomes of wildfire smoke exposure is its impact on birth weight, particularly when exposure occurs during critical periods of fetal development [2]. A study found that infants born to individuals exposed to wildfire smoke in the second and third trimesters had significantly lower birth weights than those from non-exposed pregnancies [3]. Low birth weight is a key predictor of neonatal morbidity and carries lasting consequences, including an elevated risk of metabolic disorders, cardiovascular disease, and impaired cognitive development. The physiological stressors triggered by wildfire chemicals ranging from oxidative damage to placental dysfunction can directly influence fetal growth—in particular, epigenetic modifications induced by environmental toxins can alter gene expression in ways that predispose individuals to chronic health conditions throughout the rest of their lives [4]. 

The placenta serves as the primary interface between the mother and fetus, and its dysfunction due to smoke exposure can have lasting impacts. Triggered systemic inflammation can exacerbate maternal immune responses, potentially inducing complications such as preterm labor, associated with low birth weights. A large-scale study found that pregnant individuals exposed to high levels of PM2.5 from wildfire smoke had significantly higher rates of spontaneous preterm labor compared to those unexposed [5]. 

Wildfire pollutants can lead to placental barrier impairment, reducing the transfer of essential nutrients and oxygen. This underlying mechanism involves inflammation-induced activation of stress pathways, which can trigger premature uterine contractions and cervical changes leading to early labor.

Disparities in Exposure and Vulnerability 

Individuals living in wildfire-prone regions, such as the Western United States and Australia, face higher exposure risk to wildfire smoke. In particular, those in lower-income brackets often reside in substandard housing that lacks proper insulation and air filtration systems, increasing their vulnerability to wildfire smoke infiltration. These scarcities can lead to higher indoor pollution levels, exacerbating respiratory conditions among residents. Furthermore, the destruction of affordable housing during wildfires can result in displacement, with limited options for relocation, thereby prolonging exposure to unhealthy environments.​

​Disaster preparedness plans often overlook the unique needs of reproductive health, leading to significant service disruptions during emergencies. The recent freezing of U.S. foreign aid has severely impacted healthcare services for millions of women and girls globally, including essential reproductive health services [6]. Such policy decisions not only result in increased maternal mortality, unintended pregnancies, and the spread of sexually transmitted infections but also exacerbate the already precarious conditions faced by those affected by wildfires. The destruction of health infrastructure, the displacement of communities, and the overwhelming strain placed on emergency response systems disproportionately harm pregnant individuals and those requiring reproductive healthcare. When policies restrict funding for essential services, such as emergency obstetric services, these populations are left even more vulnerable during climate-induced disasters [7]. Without federal and international support, low-income and rural communities already facing limited healthcare access before a wildfire event may find themselves entirely cut off from critical care.

Furthermore, America’s withdrawal from the World Health Organization weakens coordinated responses to wildfires and related public health crises. The WHO plays a critical role in guiding emergency preparedness by ensuring equitable distribution of aid and addressing long-term health consequences of climate-related disasters. Without their oversight, fragmented responses leave communities without standardized protocols for managing wildfire-related health risks. The absence of centralized coordination also impairs reproductive health responses during wildfires—leading to shortages in prenatal vitamins and postpartum care, particularly for displaced individuals living in shelters or makeshift housing.

In regions already suffering from environmental injustices, these policy failures perpetuate cycles of health inequities. Indigenous communities, farmworker populations, and low-income neighborhoods in wildfire-prone areas are frequently overlooked in disaster response plans, receiving delayed or insufficient aid [8]. As federal restrictions on reproductive healthcare funding continue to expand, particularly for organizations providing abortion services or comprehensive sexual health education, the intersection of environmental disasters and policy failures further marginalizes these vulnerable populations. The compounding effects of climate change, underfunded public health systems, and regressive policy decisions create a crisis where reproductive health is deprioritized—despite the reality that wildfires disproportionately harm individuals already facing systemic barriers to care.

Michelle Cheon is a first-year in Grace Hopper College.

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References

  1. Human Exposures, Health Impacts, and Mitigation. The Chemistry of Fires at the Wildland-Urban Interface. National Academies Press (US)  [Internet]. 2022 Sep 15. 6, Available from: https://www.ncbi.nlm.nih.gov/books/NBK588649/
  2. Padula, A.M. et al. Gene-environment interactions between air pollution and biotransformation enzymes and risk of birth defects. National Center for Biotechnology Information [Internet]. 2021 Feb 10; 113(9):676–686. Available from: https://doi.org/10.1002/bdr2.1880
  3. Evans, J. et al. Birth Outcomes, Health, and Health Care Needs of Childbearing Women following Wildfire Disasters: An Integrative, State-of-the-Science Review. EHP Publishing [Internet]. 2022 Aug 18; 130(8):86001. Available from: https://doi.org/10.1289/EHP10544
  4. Padula, A.M, Benmarhnia T. Wildfires in Pregnancy: Potential Threats to the Newborn. Paediatr Perinat Epidemiol. [Internet] 2021 Nov 5; 36(1):54-56. Available from: https://doi.org/10.1111/ppe.12838
  5. Basilio, E. et al. Wildfire Smoke Exposure during Pregnancy: A Review of Potential Mechanisms of Placental Toxicity, Impact on Obstetric Outcomes, and Strategies to Reduce Exposure. Int J Environ Res Public Health. [Internet] 2022 Oct 22; https://doi.org/10.3390/ijerph192113727
  6. Paun C., Lippman D. USAID cuts expected to devastate global health [Internet]. POLITICO; 2025. Available from: https://www.politico.com/news/2025/02/27/foreign-aid-cuts-usaid-hiv-malaria-00206564?utm_source
  7. Glenza G. ‘A fight for our lives’: Trump’s USAid freeze is harming millions of women and girls [Internet]. Guardian News & Media; 2025. Available from: https://www.theguardian.com/us-news/2025/feb/13/usaid-funding-freeze-health?utm_source
  8. Beckett L. The LA fires burned down a thriving Black community. Residents are afraid of being ‘erased’ [Internet]. Guardian News & Media; 2025. Available from: https://www.theguardian.com/us-news/2025/feb/16/california-fires-black-community-recovery?utm_source

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