By Whitney Akinyi

High exposure to heat during pregnancy, particularly in the third trimester, could lead to an increased risk of severe maternal morbidity (SMM), a new study has found.

SMM is a condition characterized by severe and unexpected complications during labor and delivery, considered a near-miss for maternal mortality.

The study titled Analysis of Heat Exposure During Pregnancy and Severe Maternal Morbidity sheds light on an environmental risk factor for maternal health and highlights the importance of targeted interventions, particularly for vulnerable populations.

Additionally, it found that heat waves during the final gestational week were linked to a higher risk of SMM, with the risk increasing with the severity and duration of the heatwave.

Despite advances in prenatal care and medical technology, the prevalence of SMM in the United States has been steadily rising with the rate of SMM in 2014 being nearly three times higher than it was two decades ago.

The study finds that though factors such as case identification improvements and changes in maternal demographics have been proposed as potential contributors to the rising SMM rates, they do not fully account for this upward trajectory. Researchers have thus sought to identify additional preventable risk factors, with a particular focus on climate-sensitive exposure.

Extreme heat episodes of increasing severity have become more frequent over the past few decades and have been associated with adverse pregnancy outcomes. Recent research identified high-risk clusters of SMM in South Carolina, revealing that individuals exposed to extreme heat during pregnancy were more likely to reside in these clusters. Although extreme heat has been linked to various adverse obstetric outcomes, limited evidence exists regarding individual-level SMM risk, making this study particularly groundbreaking.

In recent years, cardiovascular conditions have emerged as a leading cause of pregnancy-related deaths. This study delved into the relationship between extreme heat exposure and maternal cardiovascular conditions as they relate to SMM. Given the heightened vulnerability of pregnant women to extreme heat, this research aimed to shed light on the potential connections between heat, maternal cardiovascular health, and SMM. This information could be invaluable in designing targeted interventions to reduce heat-related SMM risks.

The researchers conducted a retrospective cohort study involving over 400,000 singleton pregnancies in Southern California from 2008 to 2018. Detailed demographic, medical, and lifestyle data were collected from electronic health records. The study identified cases of SMM during delivery hospitalization and assessed heat exposure during pregnancy.

Maternal age, education level, income, and other factors were found to modify the heat-SMM relationship. Mothers younger than 25 or older than 35, as well as those with lower educational backgrounds, exhibited higher susceptibility to heat-related SMM risks.

Access to green space, especially areas with trees or grass, appeared to lower heat-related SMM risks. While this effect was not statistically significant, it suggests that urban planning and green space initiatives could be beneficial in mitigating the impact of extreme heat on maternal health.

In a world where climate change is increasingly affecting our daily lives, understanding its impact on maternal health is crucial. This study takes a significant step forward in unraveling the complex relationship between environmental factors and maternal morbidity, offering hope for improved outcomes for expectant mothers.