Impact of heat on neonatal mortality in India

While increasing heat is a direct impact of climate change on health, epidemiological studies are quite limited in India. Here we examined the impact of heat on neonatal (children less than 28 days) and very early (children died on the first day) neonatal mortality using the fifth round of the National Family Health Survey (NHFS-5) dataset for 2019-2021. For heat exposure, we used a global daily temperature dataset at 1-km by 1-km saptial scale. First, we evaulated the global temperature dataset with station-based measurements for India and found reasonable accuracy for further application. In the NHFS-5, health and demographic information was collected from 30456 clusters spanning across urban and rural India covering every district. The estimated very early neonatal mortality and neonatal mortality values were 17.1 and 23.4 per 1000 live births, respectively. We then assinged exposure to daily maximum and minimum temperature at household level, and using a generalized logistic regression model, estimated the effect of heat after adjusting for the covariates. For every 1 degree increase in maximum and minimum temperature, very early neonatal mortality increase by 2.7% (95% CI: 1.6-3.8) and 2.0% (1.0-2.9), respectively. We found larger effect of heat on neonates born in the 'poorest' households (3.3% and 3.0% highesr risk for every 1 degree increase in maximum and minum temperature) with the effect declining (but still significant) with an increase in wealth index. We also found larger effect on male child than on female child, and on neonates in rural region than in urban region, and the effect fizzles out with a few days lag. As temperature is expected to rise further due to climate change, adequate adaptation startegy is required to protect the most vulnerable group; without which India cannot meet the sustainable development goal of reducing very early neonatal mortality and neonatal below 7 and 10 per 1000 live births, respectively, by 2030.