Peer-reviewed article
Study protocol for the Bio-HEAT study: Investigating the Biological pathways from HEAT exposure to preterm birth and other adverse maternal and child health outcomes in South Africa.
Solarin I, Lakhoo DP, Mc Alpine K, Brennan MM, Chikandiwa A et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study protocol investigates how heat exposure during pregnancy affects mothers and babies in Johannesburg, South Africa. The research will follow 200 pregnant women from mid-pregnancy through one year after birth, measuring heat exposure, environmental conditions, and biological markers in maternal blood and urine. The study aims to understand the biological pathways connecting heat stress to preterm birth and other health problems in mothers and infants. Three additional sub-studies will examine sleep and activity patterns, personal experiences, and breastmilk composition in women facing high heat stress.
Key points
- The study will monitor 200 women and their infants, tracking heat exposure through personal, community, and facility-level temperature monitors and geospatial data
- Multiple biological specimens (blood, urine, saliva) will be analysed for inflammatory markers, metabolic indicators, and hormonal levels to identify pathways from heat to preterm birth
- Infant outcomes will include neurodevelopment assessment, hospital visits, anthropometric measurements, and vital signs collected up to one year after birth
- Three nested sub-studies will use wearable devices for sleep and activity monitoring, qualitative interviews, and breastmilk composition analysis
- The research will develop conceptual frameworks and causal models to identify which women are most vulnerable to heat-related health problems and what protects them
Limitations
This is a study protocol describing planned research rather than completed results, so it cannot tell us what the actual findings will be or whether the proposed methods will work as intended. The study is limited to one location (Johannesburg) and may not reflect heat exposure effects in other African settings.
Abstract
Introduction Epidemiological evidence linking heat exposure to adverse maternal and child health outcomes is compelling. However, the biological and social mechanisms underlying these associations remain poorly understood. Understanding the pathways explaining these associations is important given rising global temperatures, and the urgent need for developing and testing adaptive interventions. Methods This transdisciplinary study in Johannesburg, South Africa, will monitor a cohort of 200 women from their second trimester until one-year postpartum, alongside their infants. Heat exposure and environmental factors will be tracked using personal, community and facility-level temperature monitors and geospatial data. Data will be collected on social conditions, medical and obstetric history, heat stress and adaptation, hydration, mental wellbeing, and sleep quality. Clinical data includes physical measurements, ultrasound, cardiotocography, and biological specimens (blood, urine, saliva) analysed for inflammatory markers, RNA, metabolic indicators, renal function and hormonal levels. Placental and cord blood analyses will assess foetal stress. Infant data will include medical history, hospital visits, neurodevelopment, anthropometric measurements, vital signs, and urine analysis. Three nested sub-studies (20-50 participants) will explore specific aspects: Sub-study 1 will use wearable devices to monitor sleep, activity, and heart rate in high-risk women; Sub-study 2 will involve qualitative interviews; and Sub-study 3 will assess breastmilk composition and volume. Planned analyses Our primary aim is to document linkages between heat exposure and inflammatory pathways that precede preterm birth. The hypothesis that heat exposure triggers maternal inflammation will be tested by analysing epigenetic changes associated with inflammatory cytokine protein and gene expression. We will investigate thermoregulation and hydration during labour. Using isotope techniques, we assess whether heat exposure alters breastmilk composition and volume. Conceptual frameworks and graphical causal models will be developed to delineate pathways of vulnerability and protective mechanisms.