ASU researcher calls attention to overlooked extreme heat issue — its effect on reproductive health
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Heat-related stress is associated with a range of health issues, from heat exhaustion and cramps to more serious conditions such as heat stroke — and, in extreme cases, even death.
In 2024, Maricopa County reported 608 heat-related fatalities, a slight decrease from the 645 deaths in 2023, potentially reflecting growing public awareness and prevention efforts.
While health and civic leaders continue to prioritize reducing heat-related deaths, one Arizona State University researcher is drawing attention to a lesser-known consequence of extreme heat: its potential impact on human fertility and reproductive health.
Alamin Molla, a graduate research assistant and PhD student in ASU’s School of Geographical Sciences and Urban Planning, argues that extreme heat is more than just an environmental hazard— it may also affect the human ability to conceive and carry pregnancies to term.
His recent forum paperA forum paper is a forward-looking academic format that raises awareness of emerging issues, based on at least some existing evidence, and aimed at broader scholarly and public audiences., "Extreme heat and human fertility: Amplified challenges in the era of climate change," recently published in the Journal of Thermal Biology, a leading peer-reviewed journal from Elsevier.
In the paper, Molla outlines several pressing concerns. He highlights growing scientific evidence that extreme heat — driven by climate change — may reduce sperm quality and concentration in men, increase miscarriage risks and delay conception in women, and worsen overall reproductive health outcomes.
These impacts, he notes, are especially pronounced among vulnerable populations, exacerbating existing health disparities.
ASU News spoke with Molla to learn more.
Note: Answers have been lightly edited for length and/or clarity.
Question: The article’s main message regrading heat stress and reproductive health is alarming, to say the least. How might these vary in developed vs. developing countries?
Answer: Existing heat-related health research has largely focused on morbidity — such as heatstroke, cardiovascular issues, respiratory distress, as well as the increased risks of heat-related deaths.
However, the far-reaching implications of extreme heat, particularly its potential impact on fertility and reproductive health, remain critically understudied. Although a few studies have tried to explore these effects, very often the studies are from high-income countries, where a high percentage of households, offices and buildings have air conditioning units, leaving a critical knowledge gap in understanding the impacts in under-resourced low- and middle-income countries. These populations typically face greater exposure to heat-related stressors and have lower adaptive capacity.
Q: Can you please elaborate on how climate change and urbanization are linked to human fertility and reproductive health issues?
A: Over the past century, global surface temperatures have risen by approximately 1 degree Celsius due to human-induced climate change, resulting in more frequent, intense and prolonged extreme heat events. Urbanization further exacerbates this issue through the formation of urban heat islands — areas where built environments retain more heat than surrounding rural regions, leading to elevated local temperatures.
These rising temperatures can have several direct and indirect effects on fertility and reproductive health. In low- and middle-income countries with agrarian economies, climate change and extreme heat events can disrupt food production, leading to nutritional deficiencies that adversely affect fertility. Furthermore, the combined effects of extreme heat, and elevated air pollution can synergistically impair reproductive health.
Q: How does extreme heat impact women’s health, particularly in low- and middle-income countries?
A: Extreme heat poses serious risks to women’s health in low- and middle-income countries, where socioeconomic vulnerabilities and limited health care infrastructure often intensify the impacts of climate change. Fertility in many of these regions is not only central to family livelihoods but also deeply tied to cultural identity and social expectations. As extreme heat increasingly undermines reproductive health, low- and middle-income countries may experience profound and unanticipated demographic shifts.
The repercussions extend beyond physical health. In many low- and middle-income countries, infertility carries a strong social stigma, often leading to emotional distress, social isolation, anxiety and depression. When extreme heat reduces fertility while cultural expectations around childbearing remain unchanged, women may be subjected to intensified physical and psychological strain. This intersection of environmental stress, reproductive pressure and mental health burden creates a compounding cycle of vulnerability for women in heat-affected regions.
Q: What can we do to have a comprehensive understanding of heat-related FRHFever-range hyperthermia effects and how could we mitigate the effects?
A: It is extremely important to emphasize four critical areas where research and policy must converge to protect reproductive health in the face of climate change.
Comprehensive research is essential to understand how extreme heat affects fertility and reproductive health. Identifying biological tipping points can guide interventions to mitigate these impacts.
Policies that mitigate heat exposure must be developed to address its detrimental impacts on reproductive health. Urban planning that integrates green spaces, reduces vehicle emissions and promotes energy-efficient cooling solutions can help lower both temperatures and heat-related risks.
Public health initiatives aimed at reducing heat-related reproductive health risks, specifically for vulnerable communities ... should prioritize improved access to cooling infrastructure, comprehensive health education and expanded reproductive health care. Additionally, public health campaigns should raise awareness about the risks of heat exposure on fertility and pregnancy outcomes, empowering individuals with information on heat-related health risks and specific mitigation measures.
Finally, mental health support services that offer counseling, peer support groups and educational resources can help individuals and families cope with the emotional toll of infertility, addressing an important but often overlooked aspect of reproductive health in heat-vulnerable communities.
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