Despite attempts to improve maternal health in the United States, maternal mortality and morbidity rates continue to rise. Maternal mortality refers to the death of a woman during pregnancy, delivery, or postpartum. Meanwhile, morbidity is defined by when a patient experiences an illness or disease. Thus, severe maternal morbidity (SMM) refers to unexpected outcomes during labor and delivery, such as kidney failure or transfusing more than four units of blood. Ongoing research endeavors aim to define associated risk factors for SMM, including advanced maternal age, lower socioeconomic status, and concurrent issues such as heart disease.
A recent study conducted with patients from Kaiser Permanente Southern California examined maternal morbidity from a new perspective: extreme heat exposure. In the context of climate change, global temperatures have been steadily increasing. According to the National Oceanic and Atmospheric Administration, 2023 was the warmest year on record since 1850. The undeniable correlation between extreme heat exposure and adverse health outcomes among individuals grappling with conditions such as heart, kidney, or lung disorders is becoming increasingly apparent. Therefore, this new study analyzed 403,602 pregnancies documented in Kaiser’s electronic health records from 2008 to 2018. Researchers filtered out 3,446 patients who experienced severe maternal morbidity. Among these patients, the researchers examined the daily maximum temperatures in their respective locations, defining heatwaves based on temperature and duration.
Image Source: steinphoto
The researchers discovered that increased long-term heat exposure throughout pregnancy was associated with a 27% increased risk of SMM. For short-term heat wave exposure during the week before birth, the association for SMM increased as the heat exposure increased. Even though there is no current causal relationship between environmental heat during pregnancy and risks for morbidity, the study was able to determine that two are associated with one another. One hypothesis suggests that elevated temperatures may induce dehydration, causing the body to compensate by increasing heart rate and placing greater demands on the cardiovascular system. However, this study on pregnant individuals was limited because the data was based solely on the patients’ residential addresses. The researchers were unable to factor in how other environmental variables including housing conditions, air conditioning availability, workplace environments, or outdoor activities would affect exposure to heat.
Climate change impacts health through various overlapping factors, extending beyond the effects of rising temperatures on pregnant individuals. Studies have also demonstrated how increasing temperatures influence disease distribution, (e.g., increasing mosquito-borne illnesses in the United States) as well as the treatment efficacy for such diseases (e.g., medications that interfere with patients’ thermoregulation). Therefore, as climate change persists and temperatures continue to rise, it becomes increasingly crucial to understand and tailor health care practices to accommodate this changing environment.
Featured Image: Victoria Andreas / Adobe Stock
