Assessment of biological vulnerability and effects of extreme heat on maternal, fetal and newborn health: implications for policy and action

Extreme heat adversely affects pregnant women and babies, and is associated with hypertension, miscarriages, stillbirths, and low-birthweight. An in-depth study is needed on pathways and the direct and indirect effects of extreme heat during pregnancy and early life, especially in developing countries where there is a dearth of existing evidence. We aim to assess the impact of extreme heat stress on maternal, fetal, and newborn health and how it interacts with confounding effects of social determinants, nutrition, and seasonal drivers. To understand the biological mechanisms of increased vulnerability to extreme heat exposure, we plan two work packages: (1) capitalisation of available large datasets and bio-banked laboratory specimens from previous large trials/studies of pregnancy outcomes: (2) prospective, population-based, birth cohort (n=6000 pregnant women) from peri-urban and rural settings in Pakistan, linking environmental heat measurements at household/individual level with serial physiological measurements in a subset (n=3000) linked to pregnancy, fetal and birth outcomes. We will also assess the processes and pathways of these effects in the subset by measuring clinical variables (including Echo, ultrasound, ECG), and urine and blood biomarkers related to adverse effects of extreme heat on maternal, fetal and newborn health.