The impact of heatwaves on maternal, neonatal and child health outcomes in Western Australian climate zones: A protocol paper for a retrospective cohort study

<ns5:p>Background Rising global temperatures have resulted in an increase in the frequency and severity of heatwaves. Pregnancy is a time of substantial physiological change and thus maternal and neonatal health outcomes are susceptible to adverse effects of heat. There is a lack of knowledge about thermoregulation in pregnancy, including how effectively pregnant people adapt in different climate contexts and what specific environmental conditions present the largest thermoregulatory challenges. The primary aim of this study is to examine the associations between exposure to heatwaves during pregnancy and maternal, neonatal, and child health outcomes in Western Australia climatic regions. Methods All neonates born in Western Australia between 1991 and 2023 will be identified from perinatal records (~960,000 neonates). Perinatal records will be linked to weather data from the ERA5 database using Statistical Area 2 geocoding to identify heatwave exposed pregnancies. Commonly used definitions of heatwave exposure will be tested against three neonatal outcomes (pre-term birth, low birth weight, and congenital anomalies). From this, a single definition will be selected to examine maternal, neonatal, and child health outcomes using linked hospital, emergency department, and education assessment data, as well as data from the Western Australian congenital anomalies and death register. The association between heatwaves during pregnancy and health outcomes will be performed using generalised estimating equations, adjusting for covariates including, but not limited to, cigarette smoking, parity, maternal age, socio-economic status, and Aboriginality where appropriate. Stratification by socio-economic status and geographic region will also be carried out. Discussion Examining the association between exposure to heatwaves in pregnancy and maternal, neonatal and child outcomes is important given the increasing frequency of heatwaves. The study will highlight which heat definitions confers the highest vulnerability as well as demographic and geographic subgroups who are particularly vulnerable to the effects of heatwaves. It will provide valuable information for future public health planning, including targets for intervention.</ns5:p>