A 26% rise in the odds of preterm birth, and the first agreed way to count it
What happened
On 21 October 2026 four international bodies launched the first agreed set of measurements for tracking how extreme heat affects pregnant women, newborn babies and children. The four are the World Health Organization, the World Meteorological Organization, UNICEF and the United Nations Population Fund. Between them they cover health, weather, children and pregnancy, which is roughly the whole problem in one room. What they have produced is not a treatment or a warning system. It is a list of things countries should count, and count in the same way. The list is grouped into four areas: routine maternal and child health records, public health surveillance, climate and health monitoring, and measures of heat exposure itself, such as air temperature. The health outcomes on the list include preterm birth, stillbirth, low birthweight, high blood pressure in pregnancy, child deaths, visits to health facilities during hot spells, and school attendance. Countries are meant to use a core set of these measures and then add others that fit their own situation. WHO is also urging every country to build heat-health plans that specifically name pregnant women, babies and children.
Why this matters
It sounds dry. It is not. Dr Pascale Allotey of WHO put the point simply: what health systems do not count, they cannot respond to. If nobody records that the maternity unit was full the week the temperature hit the thirties, nobody plans for it next summer. At the moment countries measure heat and health in different ways, or not at all. That makes it almost impossible to compare, to spot a pattern early, or to argue for money to fix something. A shared list of measurements is the unglamorous step that makes everything after it possible. The scale is the reason for the urgency. WHO says around 1.5 billion children are exposed to heatwaves. Babies under one year old lived through 389% more heatwave days in 2024 than in the baseline period of 1986 to 2005. That is not a small shift at the edges. It is a different childhood from the one their grandparents had. Bruce Gordon, who leads WHO's environment and climate department on an interim basis, made the point that heat creates new risks for health, and that older people, pregnant women, newborns and children are the least able to get away from them. A baby cannot take off a layer, move to a cooler room or say it is too hot.
What the evidence actually says
The headline figure in WHO's announcement is that extreme heat exposure is linked to a 26% increase in the **odds** of preterm birth, meaning a baby born too early. Two words there deserve care. "Odds" is a statistical measure, not the same as saying one in four pregnancies will be affected. And "linked to" means researchers found heat and early birth occurring together more often than chance would explain, after allowing for other factors. That is strong evidence of a real relationship, but it is drawn from many studies in many places, and the size of the effect varies. The framework is built on a large review published in Nature Medicine, which pooled research across 66 countries. That review found a range of harms associated with heat exposure in pregnancy, including preterm birth, stillbirth, obstetric complications, congenital anomalies and gestational diabetes. The indicators also draw on a WHO and WMO meeting held in Geneva in January 2026. What the evidence does not yet give us is a precise temperature threshold that is safe for everyone, everywhere. Risk depends on humidity, how long the heat lasts, whether nights cool down, what housing is like and whether someone has to work outside. That is exactly why a common set of measurements matters: it is how those answers get found. It is also worth saying that this is a monitoring framework, published by authoritative bodies, and openly described as a first step rather than a finished science.
Qurexa perspective
We deliver prescriptions across Lincolnshire, so hot weather is a practical problem for us, not an abstract one. Heat affects medicines. Most should be kept below 25°C, and some, such as certain insulins, eye drops and liquid antibiotics, need a fridge. A parcel left in the sun on a doorstep, or a bag left in a car boot while you finish the shopping, can get far hotter than the air around it. That is one of the honest reasons we think about timing and handover rather than just dropping things off. It also shapes who we worry about in a heatwave. The people least able to pop out for their own prescription in 30°C are often the same people the WHO framework highlights: someone late in pregnancy, a parent with a new baby, an older neighbour. Getting medicines to the door is a small thing, but on a hot week it removes one journey that was genuinely risky. If you are pregnant, or caring for a baby, and hot weather is making a trip out difficult, it is worth asking your pharmacy what delivery options exist locally. Many offer something, and it is usually free for eligible patients.
Practical advice
Nobody can control the weather. These are the things that are actually within reach. **If you are pregnant:** drink more than you think you need, and keep an eye on the colour of your urine — dark means drink more. Keep out of the sun between 11am and 3pm. Know the warning signs that need urgent advice: a bad headache that will not shift, blurred vision, sudden swelling of the face, hands or feet, or feeling your baby move less than usual. Do not sit on those. Ring your midwife or maternity unit. **If you have a baby or young child:** offer feeds or drinks more often. Never leave a child in a parked car, not even for a minute. Use a thin cloth, not a thick one, over a pram, and check on them often — a covered pram can get hotter inside than out. Signs of trouble include fewer wet nappies, a dry mouth, floppiness or unusual drowsiness. **Keep the house cooler:** close curtains on the sunny side during the day, open windows when the outside air is cooler than inside, usually overnight, and move beds to the coolest room if you can. **Look after medicines:** store them out of direct sun and below 25°C where the label says so. Never leave them in a car. Check the leaflet if you are unsure, or ask your pharmacist — it is a quick question and they will not mind. **Check on a neighbour.** It is the cheapest public health measure there is.
What to know
WHO, WMO, UNICEF and UNFPA have published the first shared list of measurements for tracking how extreme heat harms pregnant women, newborns and children. Countries are asked to count things like preterm births, stillbirths, low birthweight, pregnancy hypertension, child deaths and clinic visits during hot spells, alongside heat data. The evidence behind it is substantial: a 26% increase in the odds of preterm birth linked to extreme heat, 389% more heatwave days for babies under one in 2024 than in 1986 to 2005, and around 1.5 billion children exposed to heatwaves. This is a counting framework, not a cure, and it is honest about being a starting point. But the logic holds — a system that does not measure a harm cannot plan for it. For families, the useful actions are old-fashioned and effective: fluids, shade, cooler rooms, knowing the warning signs, storing medicines properly, and checking on people who cannot easily check on themselves. Sources: World Health Organization, "New global framework launched to track increasing health risks of extreme heat for pregnant women, newborns and children", 21 October 2026, https://www.who.int/news/item/21-10-2026-new-global-framework-launched-to-track-increasing-health-risks-of-extreme-heat-for-pregnant-women--newborns-and-children. WHO, "Priority indicators to monitor the impact of heat exposure on maternal, newborn and child health", 21 October 2026, https://www.who.int/publications/i/item/9789240125063. Nature Medicine, "A systematic review and meta-analysis of heat exposure impacts on maternal, fetal and neonatal health", 2024, https://www.nature.com/articles/s41591-024-03395-8. This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.
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