How does humid heat during pregnancy affect child growth?

Humid heat impairs the body's cooling, leading to heat stress that can stunt a child's height up to four times more than dry heat.

What are the projected impacts of climate change on child height?

Future climate scenarios predict millions more children will experience stunted growth due to increasing hot and humid weather extremes.

Which regions are most affected by humid heat during pregnancy?

South Asia was studied, but regions like the U.S. Gulf and South Atlantic states are also seeing increased dangerous humid heat days.

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Pregnancy Heat Stress Shrinks Kids

21 Dec, 2025

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Summary

Hot and humid weather during pregnancy stunts child height.
Humid heat is nearly four times worse than dry heat for growth.
Future climate scenarios predict millions more stunted children.

Exposure to hot and humid weather during pregnancy is linked to stunted child height, with humid conditions posing a significantly greater risk than dry heat. This occurs because high humidity impairs the body's natural cooling mechanism, leading to increased heat stress for both the mother and the developing fetus.

Research utilizing data from South Asia indicates that a one-standard-deviation increase in hot-humid days during the third trimester correlates with a 5.1 percent decrease in a child's height-for-age score, compared to a 1.3 percent decrease from dry heat exposure. These findings underscore the critical impact of combined heat and humidity on prenatal development.

With an ever-warming planet, regions like the Gulf states and South Atlantic states in the U.S. are experiencing more frequent dangerous humid heat days. Projections estimate millions more children could face stunted growth under future climate scenarios, highlighting a growing global health concern.