A recent study published in Nature has found that exposure to high temperatures during pregnancy, particularly during the final weeks, significantly increases the risk of delivering prematurely. With global temperatures rising, this research highlights another important, yet often overlooked, factor affecting maternal and newborn health.

What the Study Looked At

Researchers compiled data from more than 1.5 million births across 50 countries, combining satellite-based temperature data with hospital records and birth registries. They focused on daily ambient temperature during pregnancy and its relationship to gestational age at birth.

Key findings include:

• Exposure to above-average temperatures in the final week of pregnancy was associated with a 16% increased risk of preterm birth.
• The effect was strongest in the third trimester, and among mothers living in low-resource settings or without access to cooling infrastructure.
• Even short-term heat spikes (lasting a few days) raised risk, suggesting acute exposure matters as much as long-term climate trends.

Why Heat Matters

During pregnancy, a mother’s body already works harder to regulate temperature and hydration. Extreme heat can exacerbate dehydration, stress cardiovascular systems, and even trigger contractions - all of which may contribute to preterm labor.

Preterm birth (delivery before 37 weeks) is the leading cause of infant mortality worldwide and can increase the risk of complications like breathing difficulties, developmental delays, and long-term health issues.

What This Means for Moms

You may not be able to control the weather, but you can take precautions during hot spells:

• Stay hydrated and drink fluids regularly throughout the day.
• Avoid outdoor activity during peak heat hours (typically 11am–4pm).
• Use fans, air conditioning, or air purifiers with cooling functions when possible.
• Take cool showers or baths to regulate your core temperature.

If you experience signs of overheating (dizziness, headaches, rapid heart rate), it’s important to rest and contact your healthcare provider, especially during the third trimester.

The Bottom Line

Heat exposure is more than a discomfort - t’s a real, documented risk for preterm birth. As summers grow hotter, it’s critical for pregnant women to understand and mitigate heat-related stress on their bodies.

Read the research: Nature, 2024

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