Birth weight and environmental heat load: a between-population analysis.

Area of Science:

• Environmental science
• Human biology
• Public health

Background:

• Low birth weight is a significant global health concern, linked to infant morbidity and mortality.
• Factors influencing birth weight differ between Western and developing nations, including environmental heat load.
• Thermodynamic theory suggests reduced body size may be an adaptation to heat stress.

Purpose of the Study:

• To investigate the association between environmental heat load and between-population variations in birth weight.
• To test the hypothesis that higher heat stress correlates with lower birth weight.

Main Methods:

• Compiled birth weight and thermal environment data from literature for 140 populations.
• Collected data on confounding factors such as maternal height and economic status.
• Utilized statistical analysis to adjust for confounders and assess the relationship between heat stress and birth weight.

Main Results:

• A significant inverse relationship was observed between environmental heat stress and birth weight in 108 populations.
• Heat stress accounted for an additional 9.6% of the variance in birth weight between populations.
• Maternal height and per capita gross domestic product were significant confounding factors.

Conclusions:

• Findings support the hypothesis that heat stress is inversely associated with birth weight.
• Results align with previous within-population studies on heat stress and birth weight.
• Further research is recommended to determine the role of heat stress in low birth weight in developing countries.