Exposure to extreme heat associated with adverse health outcomes for pregnant women

A first-of-its-kind study led by Jun Wu, PhD, professor of environmental and occupational health at UC
Irvine Program in Public Health, found that exposure to extreme heat had an association with severe
maternal morbidity (SMM). The Centers for Disease Control and Prevention define SMM as severe and
unexpected conditions during labor and delivery, such as amniotic fluid embolism, acute myocardial
infarction, acute kidney failure, cardiac arrest, disseminated intravascular coagulation, heart failure,
severe anesthesia complications, and sepsis.

For the past few decades, extreme heat episodes have become more and more frequent. The National
Oceanic and Atmospheric Administration tracked July 2023 as the hottest on record ever. Women who
started their pregnancy in the cold season from November through April might be more vulnerable, as
they would experience the hottest period in Southern California (May-September) in their late
pregnancy. The severity and duration of extreme heat events will continue to increase and pose more
threats to pregnant women due to their susceptibility.

The research findings hope to be used to build targeted interventions that can increase awareness and
knowledge on how pregnant women can protect themselves from exposure to extreme heat.