International research has found that exposure to extreme heat during pregnancy and the first few months of life is linked to slower development of a crucial brain region in children, and more evidence is growing that climate change is having long-term effects on health.
The study, led by researchers at the Barcelona Institute for Global Health (ISGlobal) in Spain and reported in the peer-reviewed journal Environment International, shows that extended exposure to high temperatures may affect the growth of the thalamus, which is the brain’s primary region for processing sensory information, regulating movement, and supporting memory, learning, and attention.
What the Study Found
The researchers examined health and developmental data from 3,251 children in the long-running Generation R Study, a birth cohort project based in the Netherlands.
The scientists asked whether exposure to high outdoor temperatures in pregnancy and early childhood was associated with brain structure changes in later childhood.
Their findings indicate that children exposed to more extreme heat before birth and in the first months after birth experienced slower growth of the thalamus compared to children exposed to lower temperatures.
Although the study did identify a relationship, researchers emphasized that it does not prove that heat directly causes slower brain development. More work is necessary to understand the biological reasons for the study findings.
Why the Thalamus Matters
The thalamus is often referred to as the brain’s “information relay centre.” Almost all sensory signals—except smell—come through the thalamus before reaching other parts of the brain.
It is crucial in:
Processing sensory information
Learning and memory
Attention and concentration
Sleep regulation
Motor control
Cognitive development
Any disruption to its normal development could affect various aspects of neurological function as children grow.
How Heat May Affect Pregnancy
Scientists believe that extreme heat can add to the stress of pregnant women because it puts them at greater risk for dehydration, inflammation, cardiovascular strain, and less blood flow to the placenta. These physiological changes may affect fetal growth and development indirectly.
Previous studies have already linked excessive heat during pregnancy with:
Preterm birth
Low birth weight
Pregnancy complications
Increased risk of stillbirth in severe heat events
This new research brings potential brain development to the list of concerns associated with rising global temperatures.
Climate Change and Children’s Health
With climate change causing more powerful heatwaves around the world, scientists say vulnerable groups—pregnant women, infants, older people, and people with chronic illnesses—need to be protected more.
Public health experts recommend that pregnant women:
Stay hydrated.
Avoid prolonged exposure to extreme heat.
Remain indoors during peak afternoon temperatures.
Wear lightweight clothing.
Seek medical help if they feel dizzy, thirsty, or show signs of heat stress.
Need for Further Research
More studies and climate-based studies are needed to confirm the findings and better understand how temperature exposure affects the developing brain.
Although the study did not provide a cause-and-effect relationship, it does show another potential impact of climate change on future generations. Protection of pregnant women and infants from extreme heat is an ever-more pressing public health concern as global temperatures increase, experts say.
