Heat Exposure During Pregnancy May Influence Baby’s Brain Development, New Study Finds

Introduction

Rising global temperatures are creating new health concerns, especially for pregnant people and young children. A recent study suggests that exposure to higher temperatures during pregnancy and early infancy may affect the development of certain areas of the brain.

Researchers found that heat exposure during key stages of early life was associated with changes in the growth of the thalamus, a part of the brain involved in processing information, regulating sleep, and controlling alertness and consciousness.

The findings add to growing evidence that climate change may have long-term effects on human health. While more research is needed, scientists say reducing extreme heat exposure during pregnancy and infancy could become an important part of protecting child development.

Study Examines Link Between Heat Exposure and Brain Growth

The research was conducted using health and development data from 3,251 children in the Netherlands. These children were part of a long-term study that followed participants from pregnancy through childhood and adolescence.

Researchers wanted to understand whether exposure to different temperatures from conception through early childhood was linked to changes in brain development later in life.

To measure heat and cold exposure, scientists created a climate model that tracked weekly outdoor temperatures during pregnancy and monthly temperature patterns from infancy until approximately 8.5 years of age.

The team then compared temperature exposure data with brain imaging results collected through MRI scans when the children were around 10 and 14 years old.

Researchers examined 11 different brain regions to identify whether temperature changes during early development were connected to differences in brain structure.

Heat Exposure Was Linked to Thalamus Development

The study found that the thalamus was the only brain region that showed a noticeable connection with higher temperature exposure during pregnancy and infancy.

The thalamus develops early during pregnancy and plays a major role in communication between different parts of the brain. Because it requires a strong blood supply during development, researchers believe it may be particularly sensitive to environmental changes such as extreme heat.

According to the researchers, exposure to higher temperatures could potentially affect blood flow to the placenta and fetus. This may influence how the developing brain receives oxygen and nutrients during important growth periods.

The study found that children exposed to average monthly temperatures of about 69 degrees Fahrenheit during pregnancy or infancy showed slower thalamic growth between ages 9 and 15 compared with children exposed to cooler average temperatures of around 54.5 degrees Fahrenheit.

How Could Heat Affect a Developing Baby’s Brain?

Scientists are still investigating the exact biological reasons behind the connection between heat exposure and brain development. However, researchers have suggested several possible explanations.

One possibility is that high temperatures may increase stress hormone levels in pregnant individuals. These hormonal changes could affect fetal development if the placenta is less able to protect the baby from these effects.

Another theory involves serotonin, a chemical messenger in the brain that helps establish connections between the thalamus and the cerebral cortex. Extreme heat may interfere with serotonin activity, potentially affecting communication pathways involved in brain development.

These early changes may have consequences years later. Previous research has linked differences in thalamus development with certain behavioral symptoms during adolescence, including difficulties with impulse control and increased externalizing behaviors.

However, the current study did not find a connection between slower thalamus growth and differences in cognitive performance.

Climate Change and Pregnancy Health Concerns

The findings are especially important as climate change continues to increase the frequency and intensity of heatwaves around the world.

Pregnancy already places additional demands on the body, and extreme temperatures can create extra physical stress. Heat exposure can affect hydration, sleep quality, cardiovascular function, and overall comfort during pregnancy.

Experts emphasize that reducing unnecessary heat exposure may become increasingly important as global temperatures continue to rise.

Simple protective measures may include staying hydrated, avoiding prolonged outdoor activity during the hottest parts of the day, seeking cooler environments during heatwaves, and following medical advice for managing heat-related risks.

More Research Is Needed

Although the study provides important information, researchers say it does not prove that heat exposure directly causes brain development problems in every child.

Many factors influence a child’s development, including genetics, nutrition, healthcare access, environmental conditions, and overall health during pregnancy and childhood.

Future studies will need to explore whether early-life heat exposure contributes to specific neurodevelopmental conditions and whether changes in thalamus development help explain possible long-term effects.

Scientists also hope future research can identify which periods of development are most sensitive to temperature changes and what protective strategies may reduce potential risks.

Protecting Child Development in a Changing Climate

As extreme weather becomes more common, understanding how environmental conditions affect early development is becoming increasingly important.

Pregnancy and infancy are critical periods when the brain undergoes rapid growth and structural changes. Protecting vulnerable groups from excessive heat may become an important public health priority.

While researchers continue studying the relationship between temperature exposure and brain development, families can focus on practical steps to reduce heat risks and maintain healthy pregnancy environments.

The study highlights a broader message: climate change is not only an environmental issue but also a growing health concern that may affect future generations.

Conclusion

New research suggests that exposure to higher temperatures during pregnancy and early infancy may influence the development of the thalamus, a key brain region involved in information processing and regulation of sleep and awareness.

The findings do not mean that every child exposed to heat will experience developmental problems. Instead, they highlight the importance of understanding how environmental factors may interact with early human development.

As global temperatures rise, continued research and effective heat protection strategies may help support healthier outcomes for pregnant individuals, infants, and children.

Sources

1. Barcelona Institute for Global Health news release, July 13, 2026.
2. Study published in the journal Environment International, August issue.

Disclaimer

This article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Research findings describe general trends across study populations and may not apply to every individual. Pregnancy health decisions should always be discussed with a qualified healthcare professional who understands a person’s specific medical history and circumstances.