Overview
Heat-related stillbirths are an increasingly concerning outcome of global climate change, particularly in low- and middle-income countries (LMICs). Pregnant women exposed to extreme heat—especially during the second and third trimesters—are at higher risk of stillbirth, preterm labor, and other adverse birth outcomes. With rising global temperatures and limited access to cooling, healthcare, and prenatal support, developing countries are disproportionately affected.

Causes

• Maternal Hyperthermia: Elevated maternal body temperature can impair placental function and fetal development.
• Dehydration and Heat Stress: Dehydration reduces blood flow to the uterus and placenta, increasing fetal distress and risk of death.
• Agricultural and Manual Labor: Many pregnant women in developing regions work outdoors in high heat without access to rest, hydration, or shade.
• Lack of Prenatal Care: Limited access to regular check-ups means heat-related complications often go undetected.
• Poor Housing and Infrastructure: Overcrowded homes without ventilation or electricity increase indoor heat exposure.

Mechanisms of Fetal Impact

• Placental Insufficiency: Heat stress may impair nutrient and oxygen delivery to the fetus.
• Inflammatory Response: Elevated maternal temperatures may trigger systemic inflammation that can harm fetal development.
• Uterine Contractions: Heat-induced stress hormones may cause early contractions and fetal hypoxia.
• Sleep Disruption: Poor maternal sleep in heat waves further worsens health and hormonal stability.

Risk Factors

• Rural residence
• Outdoor labor occupations (farming, construction)
• Underweight or anemic mothers
• Lack of access to water and shade
• Pregnancy during summer or peak heat season

Diagnosis

• Clinical History: Stillbirth following recent heat exposure, dehydration, or physical exertion.
• Fetal Monitoring: Abnormal fetal heart rates or signs of distress prior to death.
• Exclusion of Other Causes: Infections, congenital anomalies, or preeclampsia must be ruled out.
• Verbal Autopsy Tools: Often used in rural regions to estimate cause of death when clinical records are unavailable.

Prevention and Intervention

• Education: Informing pregnant women about heat risks and protective measures.
• Hydration and Cooling Strategies: Encouraging rest during peak heat hours and access to drinking water.
• Shade and Ventilation: Creating cool spaces in clinics, homes, and workplaces.
• Community Health Workers: Mobile outreach to provide prenatal care, early warning for heatwaves, and referrals.
• Early Warning Systems: Public alerts during heatwaves to advise vulnerable populations.
• Policy Advocacy: Integrating maternal health into climate adaptation and disaster preparedness strategies.

Prognosis and Outcomes
Heat-related stillbirths are preventable. Interventions that reduce maternal heat exposure and improve prenatal care can drastically lower fetal mortality. However, without urgent climate adaptation, cases are expected to rise, especially in Africa, South Asia, and parts of Latin America.

Global Trends

• Studies in India, Pakistan, and sub-Saharan Africa show a strong correlation between high ambient temperatures and stillbirth risk.
• The Lancet Countdown on Health and Climate Change reports increasing heat-related health burdens on pregnant women.
• WHO now includes pregnant women as a priority group in heat-health action plans.