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Ambient temperature extremes and neonatal mortality: a time-stratified case-crossover analysis using Demographic and
Paul Lokubal1, Chérie Part2, Sari Kovats2
1Department of Infectious Diseases and International Health, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK.
Introduction:
Due to their underdeveloped thermoregulatory system, neonates are at increased risk of morbidity and mortality from hot and cold temperatures. Our study aimed to analyse the effects of environmental temperature on overall, very early, early and late neonatal acute mortality in five East African countries using the Demographic and Health Surveys (DHS) data.
Methods:
We obtained neonatal mortality data from the DHS conducted between 2016 and 2022, capturing births and deaths occurring between 2011 and 2022. Our outcomes were (1) overall neonatal mortality (days 0-27), (2) very early (day 0); (3) early (days 1-6) and (4) late neonatal mortality (days 7-27). Daily mean temperature was constructed from ERA5-Land and assigned at the household level. We used a time-stratified case-crossover design with distributed lag non-linear models (0-6-day lag) to estimate odds of mortality with exposure to the 5th and 95th temperature percentiles (vs the median). Country-level estimates were generated and then pooled to assess the overall association.
Results:
A total of 1373 neonatal deaths were included, over 80% of which occurred within the first 6 days of life. The association between ambient temperature and neonatal mortality was heterogeneous. In pooled analysis, the 95th and 5th percentiles were associated with increased and decreased mortality odds respectively, although estimates were imprecise. In Uganda, there was strong evidence of association between high ambient temperature (95th percentile) and overall neonatal mortality (OR=3.54; 95% CI 1.73 to 7.28) as well as early neonatal mortality (OR=3.75; 1.70 to 8.28), while odds of very early neonatal mortality increased with exposure to low temperatures (5th percentile) (OR=5.65; 1.89 to 16.69). There was no strong evidence of association in other countries.
Conclusion:
Temperature-related neonatal mortality risk differs across East African countries. Other factors may play a significant role. Future research should consider the effects of environmental temperature on neonatal mortality across different climate zones.
