Biological Pathways

Human evidence about heat-related uterine blood flow changes remains limited and inconsistent. The study hypothesizes that heat exposure can exceed maternal adaptive capacity and cause heat strain affecting maternal physiology, placental function, fetal growth, and pregnancy timing. Heat stress is associated with oxidative stress, increased cortisol, cytokines, and maternal HSP-70. Heat may impair placental vascular development and contribute to placental insufficiency and fetal growth restriction. Maternal core temperature increases of 1.5-2°C above baseline are teratogenic, especially in the first trimester.