Nearly three in four maternal healthcare workers say extreme heat-related complications among pregnant women have increased over the past five years, according to a five-country survey released as climate ministers gathered in Fiji for the last major meeting before COP31.

The poll of 1,001 obstetricians, midwives, nurses and other maternity staff in Australia, Brazil, India, the UK and Zimbabwe, commissioned by Wellcome Trust, found 73% had seen more heat-related cases or complications in pregnant women. Another 76% reported an increase in foetal or newborn health issues.

“Midwives and doctors from countries across five continents are telling us that extreme heat is affecting the health of pregnant women and newborn babies,” said Julia Gillard, Wellcome’s chair and a former Australian prime minister. “No woman should have to fear that extreme heat will harm the baby she is carrying.”

Almost all respondents said they had personally cared for a pregnant woman (98%) or a baby (99%) whose health they believed extreme heat had harmed, and 92% said they wanted more training and resources to protect pregnant women during extreme heat.

The findings were launched on Monday at the opening of Wellcome’s Birthright campaign in Fiji, on the first day of the pre-COP ministerial meeting, where UN climat chief Simon Stiell warned that “pregnancy and birth are now a new fault line in the global climate crisis.”

“Climate-driven extreme heat during pregnancy is increasingly linked to premature birth, stillbirth, low birth weight, and maternal complications,” Stiell said. “A changing climate must never be accepted as a reason pregnancy and birth become less safe.”

“Pregnancy should be a time of hope,” he added. “But for millions, it is becoming a time of anxiety, as climate impacts fill everyday life with risk.”

Over half of respondents (55%) said clearer national or international guidance would help them provide better care. Wellcome is calling on the World Health Organization (WHO) to produce its first clinical guideline on heat, pregnancy and the postpartum period, and on governments to write pregnant women and newborns into their national climate and health plans.

“As the planet continues to heat up because of anthropogenic climate change, more mothers and babies will be put at risk,” said Gillard. “Extreme heat is an invisible killer, but pregnant women must not be invisible.”

Pressure on maternity services

About a quarter of respondents, 23%, had seen pregnancy complications requiring additional monitoring or treatment that they linked to extreme heat. Among newborns, 36% reported dehydration or heat-related illness, 34% low birth weight or restricted growth and 33% difficulties with feeding, breathing or regulating body temperature.

Over a quarter (27%) said heat is making it harder for pregnant women and their families to travel to or reach care, while 29% reported a rise in urgent or emergency presentations. Some 28% said they had struggled to store medicines, supplies or equipment safely, and 24% had dealt with interruptions to electricity, water or cooling.

Health workers in Zimbabwe reported the sharpest rise, with 85% saying heat-related complications in pregnant women had increased, compared with 79% in Australia, 74% in Brazil, 66% in the UK and 62% in India.

The poll, run online by Censuswide between 17 September and 1 October, records what health workers say they have seen rather than clinical case records. Wellcome’s methodology notes the results are unweighted, not nationally representative and do not establish that heat caused individual complications.

None of the five countries surveyed is classed as low-income by the World Bank, yet pregnancy is already far deadlier in the poorest countries. About 260,000 women died during or after pregnancy and childbirth in 2023, according to WHO, and roughly 70% of those deaths occurred in sub-Saharan Africa.

A woman in a low-income country faces a one in 66 lifetime risk of dying from maternal causes, compared with one in 7,933 in a high-income country, leaving the world far off track for its 2030 target. In sub-Saharan Africa, a 15-year-old girl faces a one in 40 lifetime risk of dying from a maternal cause, according to UN estimates for 2020.

Almost 95% of maternal deaths that year occurred in low- and lower-middle-income countries, while 73 countries, most of them in Europe or Latin America and the Caribbean, were estimated to have 20 or fewer maternal deaths. Yet a 2025 review of 83 heat-health action plans from 24 countries found none from low-income economies. Only 52% named pregnant women as an at-risk group, 39% newborns and 14% postpartum or breastfeeding women.

“We already know many of the solutions to protect people, from early warning systems to cooler buildings,” said Madeleine Thomson, Wellcome’s head of climate impacts and adaptation. The challenge, she added, is reaching “those who need them most.”

A test of climate action

Ministers from more than 50 countries are meeting in Nadi until Thursday, with a leaders’ event in Tuvalu, in the last major round of talks before COP31 opens in Antalya, Türkiye, on 9 November.

Speaking at the Birthright launch, Stiell said advice to stay cool offers little to women with “no cool place to go,” and that safe childbirth already depends heavily on geography, income and access to care. “Without action, extreme heat will widen that injustice.”

His three priorities for governments are: writing pregnancy and newborn care into national adaptation, health and heat plans; turning evidence into protection through guidance, training and heat alerts; and collecting better data.

“Harm that is not counted is too easily ignored,” he said, adding that governments need data to track where the risks are rising, who is most exposed, which protections work and where finance and technology should go.

Stiell tied the issue to the fight over adaptation finance, urging governments to deliver on commitments made at COP30 in Belém, and pointed to the Belém Adaptation Indicators and Gender Action Plan as ways to measure climate-related health risks.

“A newborn’s healthy start must never depend on a family’s ability to escape the heat,” he said.

Türkiye’s presidency has made “Dynamic and Resilient Health Systems” one of 10 priority themes on its COP31 Action Agenda, and the summit will open with a dedicated Health Day.

That agenda is voluntary, however, and health has no standalone item in the negotiations. Its foothold in the formal text runs through the Global Goal on Adaptation, under which countries adopted 59 indicators at COP30, eight of them on health.

Record heat, rising risks

The survey follows a northern summer in which 33 countries recorded their hottest July on record, according to an AFP analysis of Copernicus data. The US National Oceanic and Atmospheric Administration found July 2026 tied with July 2024 as the hottest on record globally.

Last year’s Lancet Countdown estimated that there were 546,000 heat-related deaths per year over the most recent decade, and found that 84% of heatwave days between 2020 and 2024 would not have occurred without climate change.

A 2024 meta-analysis of 198 studies across 66 countries found the odds of preterm birth rose 4% for every 1°C increase in heat exposure and 26% during heatwaves. The odds of obstetric complications rose 25% during heatwaves.

“With El Niño pushing temperatures higher, the failure to act is costing lives,” said Thomson. “Extreme heat, fuelled by climate change is impacting our way of life and our health – and yet many countries are not prepared.”