Extreme heat is no longer just an environmental issue. It is becoming a significant health concern, particularly for pregnant women and individuals with endocrine disorders.
A recent study revealed that high temperatures can exacerbate conditions like gestational diabetes and thyroid disorders among pregnant women.
Study Findings
Scientists from Singapore and Britain recently concluded a review of medical research dating back to the 1940s. They found that heat affects hormones and the endocrine system, which is responsible for creating and releasing those hormones.
Associate Professor Jason Lee from the NUS Yong Loo Lin School of Medicine (NUS Medicine), who participated in the research, stated that data shows heat increases the risk of premature birth, low birth weight, stillbirth, and gestational diabetes in pregnant women. These risks may stem from inflammation and reduced blood flow to the uterus. This is because more blood is directed to the skin to help the body cool down. However, more research is needed to fully understand the mechanisms behind these effects.
One study exposed pregnant rats to a temperature of 43°C for just 15 minutes. It subsequently resulted in pups with brain malformations and decreased adrenal gland size. These findings suggest that extreme heat could have long-lasting impacts on child health, emphasizing the need for further investigation.
The Heat-Hormone Connection
Hormones play a crucial role in regulating numerous bodily functions, including blood sugar control, fertility, and overall metabolic health. However, extreme heat may disrupt these hormonal balances. A 2017 study from the United States found that higher temperatures can reduce the amount of glucose metabolized into energy, potentially increasing the prevalence of diabetes.
Additionally, a comprehensive review by researchers from Singapore and Britain, which examined medical data dating back to the 1940s, highlighted the impact of heat on the endocrine system. This system, responsible for producing and releasing hormones, can be significantly affected by rising temperatures, particularly in pregnant women.
The Role of Climate Change
As global temperatures continue to rise, the health implications of extreme heat are becoming increasingly relevant. Professor Fadil Hannan from the University of Oxford points out that there is a significant gap in our understanding of how climate change-driven heat exposure could affect endocrine health. This gap is particularly concerning for individuals living in hot climates, where access to cooled environments may be limited.
Singapore’s daily temperatures often exceed 33°C. The city-state currently designates high heat stress days based on the Wet Bulb Globe Temperature (WBGT). WBGT is a measure that considers air temperature, humidity, wind speed, and solar radiation. A separate NUS study led by Professor Lee, known as Project HeatSafe revealed that men exposed to temperatures above 29.8°C within three months of providing sperm samples had a 46% higher risk of low sperm count, indicating that heat does affect fertility.
Heat and Endocrine Disorders
Endocrine disorders, such as gestational diabetes and hyperthyroidism, may make individuals more susceptible to heat-related illnesses. Heat stress can increase the circulation of steroids from the adrenal glands, leading to higher glucose production by the liver. This, in turn, can alter body fat distribution and increase insulin resistance, potentially exacerbating diabetes.
Professor Melvin Leow from Tan Tock Seng Hospital explains that this connection between heat and diabetes is still a hypothesis and requires more human studies to quantify the risk accurately. Nevertheless, the evidence suggests that those with existing endocrine disorders may face heightened risks during extreme heat events.
A Call for Action
Given the growing body of evidence linking extreme heat to endocrine disruptions, particularly in pregnant women, it is crucial to develop strategies to mitigate these risks. Professor Fadil Hannan is currently involved in a study in India that aims to uncover how extreme heat affects pregnancy and lactation. The goal is to use the data to develop policies and actions that will protect women and their infants.
In Singapore, healthcare providers urge for vigilance, particularly during high-heat stress days. However, they have yet to see a significant link between heat and the patients they are seeing.
Dr Peter Eng, from the Peter Eng Endocrine Clinic, said: “Changes in hormones are complex and due to multiple factors, so it would be difficult to attribute any hormone change to heat alone.”
Associate Professor Chan Shiao-Yng, senior consultant at the National University Hospital’s Department of Obstetrics and Gynaecology, said: “Heat has been linked to poor pregnancy outcomes, but we are lacking robust trials to show that cooling strategies could decrease such risks.
Conclusion
As global temperatures rise, the link between extreme heat, gestational diabetes and endocrine disorders becomes increasingly critical. While more research is needed to fully understand the mechanisms at play, the current evidence underscores the importance of taking proactive measures to protect vulnerable populations, particularly pregnant women and individuals with endocrine disorders. As climate change continues to challenge our health systems, understanding and mitigating the risks associated with extreme heat must become a priority for medical professionals and policymakers alike.
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