Experts are warning about the dangerous impacts of heatwaves on pregnant women and newborn babies in the UK, as new research finds they are sweltering through twice as many dangerously hot days.
Between 2020 and 2024, an average of 26 days a year saw temperatures soar so high in the UK they posed a health risk to pregnant women, scientists at Climate Central found.
Half of these days were added by global warming, which is making hot weather even hotter.
The impact of heat on pregnancy is an understudied but rapidly growing field of research.
Studies in some parts of the world have already identified a higher risk of stillbirths, or babies being born underweight, prematurely or with defects.
In mothers, heat exposure has also been linked with hypertension, preeclampsia, gestational diabetes, breastfeeding problems and poor mental health – though experts say more research is needed.
Dr Chloe Brimicombe from the London School of Hygiene and Tropical Medicine said: “For the UK, we know a rise in temperatures can cause a rise in the risk of preterm births.
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“We should be quite concerned, as climate change is having an effect from before birth right the way through our lives, and this risk is only increasing.”
‘I felt I couldn’t keep my baby safe’
Newborns are particularly vulnerable to heat because their small bodies heat up more quickly, and they cannot cool themselves down or communicate what they need.
Mother Amy Woolfson said temperatures in her postnatal ward hit a “disturbing” 26C by 4.30am after she had given birth to her daughter in September 2023. By 10am, it was 30C.
“She was so tiny, and I didn’t feel like I could keep her safe,” she told Sky News. “I felt completely frantic.”
She could not find anywhere to keep cool, and so in the end asked to be discharged early.
“I wasn’t ready,” she said, but it “got to the point where I just wanted to go home”.
She said the intense heat “brought home” the reality of climate change.
“In the very first few days of her life, climate change is happening and is making her unsafe – and it really brought that home for me in a way that nothing ever had previously.”
Read more: ‘Tropical nights’ in European holiday hotspots are soaring
Warnings about UK hospitals
Ms Woolfson blames poor protocol and missing heat measures – and last month the country’s climate advisers warned many hospitals “already struggle to operate effectively” in heatwaves.
In 2022, record 40C temperatures led to cancelled operations, staff and bed shortages and overheating in surgical theatres.
Today’s study adds further evidence to growing concerns that Britain’s ageing hospital buildings – sometimes with a lack of fans and windows that barely open – struggle to cope in the heat.
Climate Central’s research counted the number of days hot enough to pose a risk to pregnant women, and compared them with those in a simulated environment, without global warming.
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Pregnancy heat risk days were classed as those warmer than 95% of all temperatures recorded in that location.
In the UK, the greatest abnormal exposure was in the east of England, but globally hotter and poorer countries are more vulnerable.
In underdeveloped Tuvalu in the South Pacific, climate change added all 52 of the pregnancy heat risk days.
Dr Kristina Dahl from Climate Central said climate change is “stacking the odds against healthy pregnancies worldwide, especially in places where care is already hard to access”.
She added: “These impacts on maternal and infant health are likely to worsen if we don’t stop burning fossil fuels and urgently tackle climate change.”
The study has not been published in a journal but uses peer-reviewed methods, and two independent professionals told Sky News the findings may be conservative.
Experts have called on the government to invest in hospitals, and improve heat-health plans and early warning systems.
A spokesperson for the government’s Department of Health and Social Care said: “We inherited a crumbling hospital estate that is not fit for purpose, including old buildings that are unable to cope with extreme temperature changes.
“We have set aside over £1bn to start tackling the backlog of critical maintenance, repairs and upgrades that are needed to improve things for staff and patients.
“And we have put the New Hospital Programme on a secure footing, ensuring we can deliver the hospital rebuilds needed to make our NHS fit for the future through our Plan for Change.”
