Peer-reviewed article
Biological impacts of rising temperatures on maternal, fetal and newborn health: protocol for a cohort study (BIRTH-Cohort).
Jai K Das, Asma Abdul Malik, Aris T Papageorghiou, Suneel Piryani, Mahnaz Ambareen et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study protocol describes a prospective cohort examining how heat stress during pregnancy affects maternal and newborn health in Pakistan. Researchers will follow 6,000 pregnant women across three districts in Sindh from early pregnancy through 12 months after birth, measuring heat exposure with wearable sensors and tracking fetal development and birth outcomes. The study aims to understand the biological mechanisms linking heat stress to complications like low birth weight, preterm birth, and stillbirth. A subset of 1,000 women will be monitored more intensively for heart rate, skin temperature, sleep and activity patterns throughout pregnancy.
Key points
- The study will recruit 6,000 pregnant women aged 18+ from three districts in Sindh, Pakistan, with follow-up from <14 weeks gestation to 12 months postpartum
- Primary outcomes are low birth weight and small vulnerable newborns; secondary outcomes include preterm birth, small for gestational age, miscarriage, stillbirth, and maternal and neonatal morbidity and mortality
- Heat exposure will be measured using wearable sensors and heat strain biomarkers, with fetal ultrasound and Doppler assessments at each visit to measure fetal growth and placental circulation
- A subset of 1,000 women will have continuous monitoring of heart rate, skin temperature, sleep patterns and physical activity using wearable devices
- Time-varying, distributed lag and non-linear models will examine associations between heat stress indices and pregnancy outcomes
Limitations
This is a study protocol rather than results, so it cannot yet tell us what the actual findings are or whether the hypothesised biological mechanisms linking heat stress to adverse outcomes will be confirmed. The study is limited to Sindh province in Pakistan, so findings may not generalise to other geographic regions or populations with different levels of heat exposure or healthcare access.
Abstract
INTRODUCTION: Climate change has led to extreme heat events, disproportionately affecting vulnerable populations. Heat stress during pregnancy is linked to adverse health outcomes, yet the biological mechanisms remain poorly understood. This research study aims to investigate the effect of environmental heat on maternal, fetal and infant health and examine the biological pathways linking heat stress to adverse pregnancy outcomes. METHODS AND ANALYSIS: This prospective cohort study will recruit 6000 pregnant women from three districts in Sindh, Pakistan. Eligible participants ≥18 years old, will have a minimum of five scheduled visits from <14 weeks' gestation and will be followed up to 12 months postpartum. Primary outcomes include low birth weight and small vulnerable newborns (SVN); secondary outcomes include preterm birth, small for gestational age (SGA), miscarriage, stillbirth, and composite maternal and neonatal morbidity and mortality. Fetal ultrasound scans with Doppler assessments will be performed at each visit to measure fetal growth, uteroplacental and fetoplacental circulation. Each woman's heat exposure will be measured using wearable sensors and heat strain biomarkers. In a subset of 1000 women, maternal heart rate, skin temperature sleep patterns and physical activity will be monitored throughout pregnancy using wearable devices. Time-varying, distributed lag and non-linear models will examine associations between heat stress indices and pregnancy outcomes. ETHICS AND DISSEMINATION: The study has received ethical approval from the Aga Khan University (AKU) (Ref: 26249) and the Pakistan National Bioethics Committee (Ref: 1065/23/1736). Written informed consent will be obtained from all participants before enrolment. Referral pathways to healthcare facilities will be established to ensure timely management of pregnancy complications. Findings will be disseminated through peer-reviewed publications, scientific conferences, and engagement with policymakers and public health stakeholders to inform climate-resilient maternal health strategies. Results will also be shared with participants and communities through meetings and informal sessions to raise awareness and support evidence-based heat adaptation. TRIAL REGISTRATION NUMBER: NCT01234567.