Wellcome survey: 73 percent of maternal health workers report more heat-linked complications

Simon Stiell, the UN climate chief, told a Wellcome event in Nadi, Fiji, on Monday that a new survey of maternal health workers should change what ministers argue about at COP31. The survey, commissioned by Wellcome and taken in five countries on five continents, found that 73 percent of the professionals asked said heat-linked cases or complications in pregnancy had increased over the past five years. Stiell spoke on the first day of the official Pre-COP ministerial meeting.

He listed the outcomes clinicians are tying to extreme heat in pregnancy: premature birth, stillbirth, low birth weight and maternal complications. He said the last 11 years had broken heat records, and he treated El Niño conditions as a reminder of how fast heat and disruption can intensify. The line he asked ministers to carry was that pregnancy and birth are now a fault line in the climate crisis, and one that can kill.

What the 73 percent does and does not say

A survey of professionals is not a count of births. It records what midwives, obstetricians and related staff say they are seeing. Seventy-three percent reporting an increase is a large share of the people Wellcome asked. It does not produce a rate per thousand births, and Wellcome's public note on the Nadi event did not publish the sample size or the five country names in the remarks Stiell read. Those gaps matter for anyone who wants to turn the figure into a global incidence. They do not erase the figure as a field report from the people who manage labour wards.

Heat hits pregnancy through a few plain mechanisms. A raised core temperature late in pregnancy is associated with earlier labour. Dehydration and cardiovascular strain raise the risk of hypertensive episodes. In places without reliable power, a heat wave also shuts the fans and the cold chain for oxytocin and blood. The survey's value, if the underlying tables are released, will be whether clinicians in the five countries are describing the same complications or a mix of preterm labour, stillbirth and maternal collapse that varies by ward.

Where this sits in the COP31 design

Stiell commended the COP31 presidency of Turkey, working with Australia as president of the negotiations, for making health a priority and for building on Brazil's work at the previous summit. The split presidency is the structural fact of this cycle: Turkey holds the presidency, Australia runs the negotiating track. A health day that features pregnancy is a choice about the agenda, not a decision about finance. The money question at COP31 remains the same one left open in Brazil: who pays for adaptation in hospitals and clinics that lose power on the hottest days.

Pre-COP in Nadi is a ministerial filter. What survives the week in Fiji is what arrives in the draft texts. A 73 percent figure from a five-country survey is the kind of number that can enter a preamble and still leave the operative paragraphs on finance untouched. Stiell's speech put the clinical observation on the table. The test, over the next weeks, is whether Turkey and Australia give it a line in the decision or leave it in the side-event record.