1. Introduction
In recent decades, the consequences of global climate change have become increasingly apparent, with extreme heat events posing a substantial risk to human health. Heatwaves are now more frequent, more intense, and longer-lasting, affecting both urban and rural populations across all continents. Public health frameworks often prioritize senior adults, infants, and individuals with preexisting conditions as heat-vulnerable groups. However, pregnant individuals are frequently overlooked, despite evidence that gestation leads to unique physiological challenges that may exacerbate heat-related morbidity.
Emerging data suggests that exposure to high ambient temperatures during pregnancy is associated with a range of adverse maternal and fetal outcomes, yet targeted strategies for prevention and intervention remain scarce (1). Given the projected trajectory of climate change, understanding the implications of heat exposure during pregnancy has become an urgent public health priority.
2. Maternal and Fetal Risks Associated with Heat Exposure
Several epidemiological studies have linked extreme heat exposure to increased risks during pregnancy. Documented adverse outcomes include:
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Preterm birth: Elevated ambient temperatures have been associated with an increased incidence of spontaneous and medically indicated preterm deliveries, likely mediated by maternal dehydration, inflammatory responses, or placental insufficiency (2,3).
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Low birth weight: Exposure to heat stress, particularly during the third trimester, has been linked to reduced fetal growth, resulting in lower birth weight and potential long-term developmental consequences (2,3).
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Stillbirth: An association was found between extreme heat and stillbirth, with an increase of 5 % probability of stillbirth by a rise of 1 degree in temperature (2,4).
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Congenital anomalies: There is growing evidence that maternal exposure to extreme heat, especially during the first trimester, may increase the risk of congenital anomalies. Congenital cardiac defects are among the most frequently reported anomalies (5).
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Gestational diabetes mellitus (GDM): Some studies have observed an increased prevalence of GDM among individuals with sustained exposure to high temperatures, though the underlying mechanisms remain unclear (5).
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Hypertensive disorders and cardiovascular complications: Heat exposure may increase the risk of hypertensive disorders in pregnancy, including early-onset preeclampsia. In extreme cases, heat exposure can exacerbate underlying cardiovascular conditions, occasionally leading to severe outcomes such as arrhythmia or cardiac arrest (1).
3. Physiological Mechanisms and Increased Susceptibility
Pregnancy involves complex physiological changes that may impair thermoregulation and increase susceptibility to heat-related illnesses. These include:
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Increased basal metabolic rate and maternal core temperature
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Expanded plasma volume and increased cardiac output
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Altered fluid and electrolyte balance
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Decreased capacity for heat dissipation via cutaneous vasodilation and sweating
These changes make pregnant individuals more vulnerable to dehydration, heat exhaustion, and heatstroke. Furthermore, the fetus lacks independent thermoregulatory capacity and is reliant on maternal homeostasis, making intrauterine exposure to heat a significant risk factor for developmental disruption.
4. Current Gaps in Public Health Planning
Despite the growing body of evidence, maternal health is seldom incorporated into national or global heat adaptation strategies. A 2025 scoping review of Heat Health Action Plans (HHAPs) found that maternal, newborn, and child health were rarely addressed as priority areas (6). This omission is particularly problematic in low-resource settings, where structural inequities and limited access to care further exacerbate risk.
Moreover, existing clinical guidelines in obstetrics often fail to include environmental risk assessments or heat-specific recommendations, leaving healthcare providers without standardized protocols for managing pregnant individuals during heat events.
5. Recommendations for Clinical and Policy Action
A coordinated response is needed across clinical care, urban planning, and public health policy to protect pregnant individuals from heat-related harm. Recommended actions include:
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Patient education: During routine antenatal visits, healthcare providers should counsel pregnant individuals on heat avoidance, adequate hydration, and early signs of heat illness.
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Enhanced access to cooling resources: Public health systems must ensure equal access to air-conditioned spaces and cooling centers during heatwaves, with priority given to vulnerable populations, including pregnant individuals.
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Environmental risk screening in prenatal care: Antenatal assessments should include questions about occupational and residential heat exposure, housing quality, and access to cooling.
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Urban heat mitigation: Urban planning should prioritize the development of green infrastructure, shaded public spaces, and heat-resilient housing, especially in underserved communities.
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Policy integration: Maternal health must be explicitly addressed in national climate adaptation frameworks, emergency response plans, and heat alert systems.
6. Conclusion
As climate change progresses, the burden of heat-related health complications during pregnancy will likely increase. It is imperative that public health systems recognize pregnant individuals as a heat-vulnerable population and implement both clinical and systemic interventions to mitigate risk. Collaboration of healthcare providers, researchers, urban planners, and policymakers will be essential in developing and deploying comprehensive, equity-focused strategies.
By proactively addressing the intersection of extreme heat and pregnancy, we can protect maternal and fetal health in an increasingly hostile climate environment — and ensure that pregnancy is supported, not endangered, by the systems intended to safeguard it.
Contributors
Joep Neven contributed to drafting the manuscript.
Chantal Quispel contributed to revising the article critically for important intellectual content.
Both authors approved the final submitted manuscript.
Provenance and peer review
This editorial was commissioned and not externally peer reviewed.
Funding
No funding from an external source supported the publication of this editorial.
Declaration of competing interest
The authors declare that they have no competing interest regarding the publication of this editorial.
References
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