Not only cold but also heat: the effect of maternal exposure to high temperatures during gestation on neonatal mortality in pre-transitional Casalguidi, 1819–1859

Abstract Consideration of weather and the environment is becoming increasingly prominent in the field of historical demography. Early studies on infant mortality have paved the way for this type of analysis, shedding light on the significant impact of cold weather conditions on child survival. However, recent research on contemporary populations has drawn attention to the increased risk of adverse birth outcomes due to maternal exposure to heat during pregnancy. The present study aims to validate this finding in a pre-transitional population, specifically focusing on its effects on neonatal mortality. To our knowledge, this analysis is being applied to such populations for the first time, with the goal of exploring whether factors other than cold winters may have also influenced mortality mechanisms during this crucial life stage in historical populations. The results show that heat exposure significantly affected early neonatal mortality, and they also reveal that the susceptibility window was limited to the second trimester of gestation. Temperature-related risks of death were influenced by the tie the family had to the land, with sharecroppers being at the lowest risk. This finding was attributed more to cultural elements associated with the value of children within this social group than to purely economic factors related to living conditions.