The Unequal Burden of Extreme Heat

As temperatures continue to rise due to global warming, extreme heat is an ever-increasing threat to sensitive groups; in the US, extreme heat causes more deaths annually than any other weather-related hazard. The Children's Development and Health Institute reports that two-thirds of the U.S. population live in counties susceptible to health issues from high temperatures, leading to heatstroke, heat exhaustion, and worsened respiratory and cardiovascular illnesses. Rising greenhouse gas levels and poor air quality exacerbate these conditions, highlighting the need for a multifaceted approach to climate change.

While the effects of rising temperatures on the elderly and those with chronic illnesses are well-documented, the unique risks to children, especially during gestation and early childhood, must also be understood. Research suggests that the mortality rate for infants and children under five may be elevated during heat waves. Additionally, studies indicate that heat-related hospital admissions for children under 18 increase during the summer months. These impacts are related to unique biological differences that make this population more sensitive to heat, and less able to modulate their behaviors in response to overheating. 

Racial discrimination in the US contributes to poorer health outcomes for pregnant individuals of color, and extreme heat is a multiplier of this. Research shows the relationship between “racially-oppressed groups, socio-economic inequalities,” and increased rates of pregnancy-related mortality. This article explores the vulnerabilities of pregnant people and young children to extreme heat, and highlights opportunities for local governments to mitigate these impacts effectively. It also applies a health equity lens to recognize how disparate these impacts can be across race/ethnicity and income levels.

Impacts by Developmental Stages

Early exposure to extreme heat, air pollutants, or other environmental toxins significantly shape lifelong health and development. The prenatal and early childhood periods are crucial developmental points for young biological systems.

Pregnancy: Pregnant people face increased personal risks during extreme heat, making them more likely to experience heat exhaustion, heat stroke, and dehydration. Extreme heat can exacerbate pregnancy swelling and affect blood flow, and even increase the risk of high blood pressure and preeclampsia. There is also a risk of heart problems during labor and delivery due to extreme heat exposure during pregnancy. 

Fetal: Of course, there is a direct relationship between the gestational carrier’s health and exposure to heat and the fetus’ development and health. While there are a few biological factors that influence prenatal temperatures, fetal core temperature is roughly  0.5°C higher than the pregnant person’s; one factor is the flow of blood through the placenta which can decrease during extreme heat. Summary research shows that there is a 16 percent increased risk of preterm birth during heat wave days, which leads to cascading effects. Low birthweight and stillbirths are also more likely during heat waves and higher-than-normal temperatures.  

Neonatal: Infants are acutely vulnerable to extreme heat due to their smaller body size and less efficient thermoregulation. High temperatures can lead to dehydration, heat exhaustion, and heatstroke, with infants being particularly susceptible to heat-related mortality. Exposure to heat waves during the perinatal period has been proven to cause renal diseases, electrolyte imbalances, and respiratory problems, among others. 

Early childhood: Heat impairs learning and cognitive function in children, in part because it also affects sleep quality. Chronic heat exposure disrupts sleep patterns and increases stress levels, which can result in behavioral issues in the short-term and can potentially lead to long-term emotional, physical, and cognitive difficulties for youth. Research shows that children's cognitive performance declines with higher temperatures, with significant drops in academic performance on days exceeding 90°F. 

Interventions for Sensitive Populations

Since the impact of heat varies based on a variety of factors, city-level interventions must address the needs of specific populations and places.

Immediate Protection: During extreme heat periods pregnant people, babies, and young children must be able to cool off in the places they live, work, and go to school. Solutions include heat wave alert systems that are specifically sent to pregnant people or cooling assistance benefits for anyone eligible for programs like the Special Supplemental Nutrition Program for Women, Infants, and Children. It can also include ensuring that schools and childcare centers have adequate air conditioning through opening up libraries and community spaces as cooling centers during the summer. There are few heat protections for workers, particularly outdoor workers, but the Occupational Safety and Health Administration (OSHA) does provide guidance for preventing heat illness among pregnant workers. 

Adaptations: Infrastructure updates and strategic urban planning are crucial for mitigating the consequences of extreme heat among sensitive populations. Many city leaders are already planting trees, painting cool roofs, and creating shade structures; policymakers and community members should consider where individuals spend most of their time during pregnancy and childhood and target interventions accordingly. For example, the LA Living Schoolyards Coalition transformed asphalt schoolyards into greener spaces, reducing temperatures and improving learning environments.

Long-term Prevention: Long-term goals include reducing overall emissions and developing more resilient structures, both in terms of physical infrastructure and healthcare systems. To address the root causes of urban heat, local leaders can promote renewable energy, electric fleets, and low-emission zones as well as dedicate an individual or team to climate or extreme heat work. And it is crucial to explicitly include pregnant people during long-term heat planning, as they have often been left out. 

Lastly, heat amplifies existing inequities in housing, population density, race/ethnicity, and economic opportunity, burdening low-income and marginalized communities. Even when controlling for things like education, factors like race have an enormous impact during high heat events. For instance, children born to Black women (with college degrees) who were exposed to heat waves experienced a higher relative risk of preterm birth compared to White women (again, with college degrees) in a heat wave. Any long-term heat mitigation work must take into account, and work to overcome, these realities.

Overcoming Challenges Through Collaboration

There are challenges in coordinating a multi-pronged approach to a cross-cutting problem, and it can be especially difficult when the affected population isn’t tied to a certain location or job. However, since pregnancy is inherently a medical state and most infants and children receive pediatric care, partnering with healthcare facilities and providers is highly recommended. The federal Maternal, Infant, and Early Childhood Home Visiting (MIECHV) Program and Healthy Start are both models for providing care. The Home Visiting Program “awards grants to states and territories to create state-wide networks that support and carry out HHS-approved evidence-based home visiting models,” while Healthy Start “provides direct funding to local entities” in communities where infants die more often than the national average. These programs could also be avenues to discuss the dangers of extreme heat, available assistance, and location of cooling centers.  

The programs above operate on an opt-in basis, which means they reach only a portion of pregnant people and infants/children. Accessing detailed public health or medical data is difficult due to privacy concerns, but by establishing partnerships between healthcare providers and medical centers, local governments can start to gather relevant data and implement targeted interventions. For example, while imperfect, hospital admissions and death certificates are used to link temperature variations to health outcomes. By partnering with providers, local leaders can not only gain valuable longitudinal insights, but also immediately address the targeted population.  

Partnering with local relevant parties is crucial, and the effectiveness of interventions is determined by the involvement of local partners. Leveraging both local knowledge,trust and engagement with residents in policy planning ensures a more widely accepted and successful outcome. For example, local governments could promote collaboration with schools to engage young people in devising cooling strategies to protect cognitive and emotional health. Local governments can also utilize local, grassroots parent networks to check in on each other during heat events and offer assistance with at-home adaptations like installing air conditioning or shade.  

Addressing the invisible impacts of extreme heat during climate change on early childhood and pregnancy is paramount. Evidence underscores the vulnerabilities of pregnant individuals and infants to heat-related health risks. Immediate and long-term policies such as sustainable urban planning, community engagement, and equitable access to cooling systems are essential. Policymakers and partner institutions should prioritize vulnerable groups to ensure comprehensive protection, creating resilience against the threat of extreme heat. And local leaders, healthcare providers, and community organizations should actively collaborate on heat mitigation and healthcare provision for these vulnerable groups.

Sofia Fiorentino assisted with research for this article.