Rising heat exposure threatens maternal and newborn health, requiring urgent interventions

Posted on: 25 November 2024

With global temperatures continuing to break records, year after year,  there is an urgent need for research into the health impacts of climate change.  Despite a growing body of evidence, a definitive and robust picture of the impacts of heat exposure on maternal and newborn health has been missing. 

Now, researchers at Trinity College Dublin,  in partnership with Wits Planetary Health Research Division in South Africa, aim to bridge this knowledge gap, providing a robust summary of all published literature to date. Their systematic review, covering 23 outcomes, in 66 countries across 198 studies has now been published open-access in the esteemed journal, Nature Medicine. 

The team have uncovered serious and wide-ranging health risks for pregnant women and their babies in the largest systematic review of its kind. 

The researchers concluded that rising heat exposure increases the risk of:

• preterm birth 
• stillbirth 
• low birth weight
• hypertension and diabetes in pregnancy, 
• mental illness
• infections 
• congenital anomalies
• obstetric complications. 

Methodology

The team comprehensively quantify the risks and specific periods of susceptibility associated with heat exposure during pregnancy, and make clear the urgent need to protect pregnant women and their babies. They wanted to better understand the different periods of vulnerabilities, and the unequal impacts of climate change on vulnerable communities. 

Findings

• For every 1°C increase in temperature, the odds of preterm birth rose by 4%, and during heatwaves, the odds increased by 26%. 
• When comparing these impacts between high-income and lower-income countries, they found a 50% difference in the size of the effect, highlighting the unequal effects of climate change. 
•  Rising temperatures were associated with a 28% higher risk of gestational diabetes and nearly 50% increased risk of congenital anomalies.
•  These are not just percentages but represent real increases in the number of adverse outcomes, due to heat, with major social and economic impacts.
•  Increases in the burden of these illnesses threatens to undo decades of progress in protecting the health of pregnant women and their babies. 

Professor Matthew Chersich, Research Fellow (Public Health & Primary Care), School of Medicine, Trinity College, and executive director at Wits PHR, said: 

“Our research provides compelling evidence that heat exposure poses severe health risks for pregnant women and their babies, yet these risks are frequently underestimated, or simply ignored. We are failing to uphold our principal oath as public health practitioners: to protect the wellbeing of the most vulnerable. It is time for a public health response to this public health emergency.”

​Professor Chersich is leading a new group of international researchers at Trinity College Dublin who are developing novel solutions to understand, monitor and respond to the climate change crisis.

A call to action

This landmark study is released as world leaders conclude negotiations at COP29, with an increasing emphasis on the health impacts of climate change. It is clear that we are in need of urgent, tangible actions to safeguard the health of those most vulnerable. The time for negotiation is finished; it is now time to act.  

Although vulnerable groups in the Global South are most affected by rising heat, this is a crisis that affects everyone. Our results are reported relative to the average temperature, so whether we’re looking at Ireland or Spain, the increase of 1.5°C due to Climate Change is already having an effect.

Lead author, Dr. Darshnika Lakhoo, a research clinician at Wits PHR  , said: 

“This is a pivotal moment for public health and climate action. Protecting the health of pregnant women and newborns must become a priority in our response to climate change.  We hope these findings will catalyse change at the policy level, ensuring at-risk populations receive the support they need.”

Next steps  

This is a 'living' review, with updates planned every 18–24 months to ensure that new data from this rapidly growing field is integrated to inform our understanding of these critical health risks. Further to this, through their global consortium, they are addressing the research gaps through work in the HE²AT Center, HAPI, HIGH Horizons, GHAP and BioHEAT projects .

You can read the review: Systematic review and meta-analysis of heat exposure impacts on maternal, fetal, and neonatal health’ in Nature Medicine, at this link: https://www.nature.com/articles/s41591-024-03395-8

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