Extreme heat increasing risks for pregnant women and babies, experts warn

**Lead**

Pregnant women and their unborn babies face mounting health risks as extreme heat events become more frequent and intense across the United Kingdom, experts have warned. The combination of rising average temperatures and more prolonged heatwaves is placing additional strain on maternal physiology, increasing the likelihood of complications such as preterm labour, low birth weight and, in the most severe cases, stillbirth. The warning comes as the Met Office confirms that the UK’s climate is warming faster than many other parts of the world, with 2022 marking the first time temperatures exceeded 40°C in the country.

**Context**

Pregnancy already places considerable demands on a woman’s body. The cardiovascular system works harder to support the growing foetus, and the body’s ability to regulate temperature is altered. When ambient temperatures rise sharply, pregnant women are less able to dissipate heat through sweating and increased blood flow to the skin. This can lead to dehydration, reduced blood flow to the placenta, and systemic inflammation – all of which are known triggers for early labour and impaired foetal development.

Research published in leading medical journals over the past decade has consistently found a correlation between high ambient temperatures and adverse birth outcomes. A study examining birth records in London, for instance, found that the risk of preterm birth rose significantly during heatwaves, particularly among women from lower-income neighbourhoods where housing is often poorly insulated and lacks adequate cooling. Similar patterns have been observed in other UK cities, including Birmingham and Manchester.

The Royal College of Obstetricians and Gynaecologists (RCOG) has issued guidance for clinicians on managing heat-related risks during pregnancy, advising that women stay hydrated, avoid strenuous activity during peak heat hours, and use fans or cool cloths. However, experts argue that individual advice alone is insufficient when entire communities are exposed to dangerously high temperatures for days on end.

**Analise**

The implications of this trend extend far beyond individual health outcomes. Preterm birth and low birth weight are associated with lifelong health challenges, including respiratory problems, neurodevelopmental delays, and increased risk of chronic diseases such as diabetes and hypertension. The economic burden on the NHS and social care system is substantial, with neonatal intensive care costs running into millions of pounds each year for heat-related complications that are, in principle, preventable.

Moreover, the risks are not distributed evenly. Pregnant women living in urban heat islands – areas with limited green space and high concentrations of concrete and asphalt – experience temperatures several degrees higher than surrounding suburbs. Those in poorly maintained social housing or temporary accommodation are particularly vulnerable, as they may lack access to fans, air conditioning, or even the ability to open windows safely. The intersection of climate vulnerability and socioeconomic inequality means that the poorest mothers and babies are bearing the brunt of a warming climate.

Public health authorities, including the UK Health Security Agency (UKHSA), have developed heat-health alert systems that trigger advice and support when temperatures exceed certain thresholds. Yet these alerts currently do not include specific, mandatory measures for maternity services. Campaigners and medical bodies are calling for the integration of heat risk assessments into routine antenatal care, the provision of cooling shelters in deprived areas, and the retrofitting of housing to improve thermal efficiency. Without such structural interventions, the number of heat-related adverse birth outcomes is expected to rise as global temperatures continue to climb.

**Fontes**

- Royal College of Obstetricians and Gynaecologists (RCOG) – guidance on heat and pregnancy. - UK Health Security Agency (UKHSA) – heat-health alert system and public health advice. - Met Office – UK climate projections and temperature records. - Published research in *The Lancet Planetary Health* and *BJOG: An International Journal of Obstetrics & Gynaecology* on heat and birth outcomes. - World Health Organization (WHO) – general information on climate change and maternal health.