Pregnant women in Southern Africa face a higher risk of preterm and still birth due to rising temperatures than their counterparts in the Global North, according to new research from the Wits University Planetary Health Research Unit and Trinity College Dublin.
Led by Professor Mathew Chersich, widely regarded one of the world’s foremost experts on climate-health interactions, the research warns that climate change is already negatively impacting multiple maternal, foetal and neonatal health outcomes across South Africa, reports Chris Bateman for MedicalBrief.
“Climate change is not a future threat. It’s already affecting health outcomes,” said Dr Nicholas Brink, co-leader of the Wits Planetary Health team.
“Pregnant women in hot provinces face the greatest risks, especially in areas hit by repeated drought and heatwaves.”
Five South African provinces have been declared drought disaster areas in recent years.(1)
An estimated 1.3m women fall pregnant in South Africa each year – around 33 900 of them under the age of 17, and some 600 aged between 10 and 13. Many live in regions vulnerable to extreme weather patterns.
Partnering with the Clinton Health Access Initiative (CHAI) and Discovery Health’s data banks, Brink’s team is collecting data on how heat affects the physical and mental health of pregnant women. A recent innovation is CHAI’s “Smart Climate” mobile app, which integrates with the widely used Mom Connect maternal health platform. With over 420 000 users, Mom Connect allows public sector clinics to send tailored messages to pregnant women based on location, stage of pregnancy and newborn age.
Smart Climate generates alerts during heatwaves, encouraging vulnerable mothers to visit nearby clinics. According to CHAI associate Elizabeth Leonard, climate stressors like heat, air pollution, and vector-borne diseases are already causing miscarriages, poor birth outcomes and infant mortality.
Leonard emphasised the need for mitigation – cutting emissions – and adaptation, (adjusting to climate’s current and future health impacts). The app focuses on the latter.
Weather SA defines a heatwave as a temperature at least 5°C above the average maximum for the hottest month, lasting three days or more. The Wits team is using machine learning and geo-mapping to identify population groups most at risk. A pilot project is currently underway in Johannesburg.
Their global meta-analysis of 198 studies across 66 countries found that pregnant women in low- and middle-income countries face a 50% greater risk of adverse outcomes than those in wealthier nations. In Southern Africa, each ton of carbon emitted is associated with roughly 100 preterm births.
Brink says the biggest finding so far is a marked increase in preterm births – up to 25% more – following heatwaves. While proving causality in public health is notoriously difficult, he said the team was isolating variables to better understand the specific biological mechanisms at play. “In pregnancy, the immune system is suppressed to protect the foetus, which is essentially a foreign body,” Brink explained.
“Heat causes inflammation, and that inflammation disrupts the endocrine and immune pathways that regulate pregnancy timing. This can trigger premature labour.”
The team is now comparing data between low- and high-income areas of Johannesburg, with plans to expand to other provinces hit by heatwaves.
Their research also reveals how climate change exacerbates inequality. For example, leafy, well-drained Sandton contrasts sharply with flood-prone, densely populated Alexandra, where poor drainage and fewer green spaces leave residents more exposed to heat-related illness and chronic conditions.
The Wits meta-analysis shows “clear and sizable relationships” between heat and poor maternal, foetal and neonatal outcomes. It warns of a systemic failure to protect vulnerable populations like pregnant women and newborns. Urgent recommendations include:
• Early heatwave warnings;
• Cooling and hydration initiatives;
• Behaviour-change campaigns;
• Improved surveillance; and
• Better urban planning and facility upgrades.
“Health leaders need to influence sectors like housing, transport and energy if we’re serious about protecting future generations,” the researchers conclude.
Another worrying finding: extreme heat doesn’t just affect pregnant women – it also impacts healthcare quality. Heat-stricken health workers experience exhaustion and dehydration, reducing their capacity to deliver care. This compounds the burden on the system, contributing to congenital conditions, hypertension and infant mortality.
“We’re seeing a ‘double whammy’: physiological stress on mother and child, and reduced quality of care due to heat-fatigued staff,” said Brink. He cited historical data from Sweden to demonstrate heat’s effects. While Swedes now spend much of their time in climate-controlled buildings, earlier studies – before widespread air conditioning – linked high temperatures to spikes in illness.
So how is South Africa doing in response? “We’re far behind,” said Brink bluntly. “There’s growing awareness, but lived experience, particularly of pregnant women, is still not on the radar for most policymakers. Funding is another barrier. There’s plenty pledged but little dispersed. The Global Fund has done well, but we’ve come late to the party.”
What’s needed, he insists, is a transformative shift – one that enables testing, scaling, and implementing effective interventions through co-ordinated, cross-cutting action. One stark example is Tintswalo Hospital in Mpumalanga, which struggles with water and power reliability; two critical lifelines during extreme heat. “Their backup generators overheat after a few days of high temperatures,” Brink noted. “Climate change threatens hospitals at a fundamental level.” From rising maternal complications to healthcare system strain, the message from researchers is clear: climate change is already killing, and South Africa must act now to save lives.