April 2024 heatwave linked to 5,515 excess preterm births: Study

Extreme heat in April 2024 was associated with an estimated 5,515 excess preterm births in Bangladesh, an 11.9% increase on a typical April, according to a study by international research organisation Zero Carbon Analytics (ZCA).
Of these, 1,479 were attributable to additional warming caused by human-induced climate change. The report, released on Monday, said such change had made the April 2024 heat event about 45 times more likely.
The heatwave was linked to roughly 19 additional preterm births per 1,000 deliveries, the highest rate among the three countries examined: Bangladesh, India and the Philippines. Bangladesh already has the world's highest national average preterm birth rate. An estimated 16.2% of babies born here in 2020 were premature, against 13.2% across South Asia.
A preterm birth is one before 37 completed weeks of pregnancy. It is the leading cause of neonatal mortality globally, and survivors face higher risks of long-term physical and neurodevelopmental complications.
Regional variation
Dhaka and Chattogram divisions together accounted for 47% of the excess cases. Mymensingh recorded the sharpest temperature rise, averaging 3.59 degrees Celsius above the usual April baseline, and the highest rate of excess preterm births, at 24 per 1,000 deliveries, although it ranked sixth in total cases. Sylhet had the lowest rate, at 16 per 1,000. The estimated increase in risk ranged from 10% to 15% across all eight divisions.
Mid-century projections

The study projects about 1,500 excess preterm births in an average April by 2041–2060, compared with the 1985–2014 baseline, within a range of 630 to 2,900. April temperatures are expected to rise by around 1.1 degrees Celsius. Dhaka is projected to bear the highest burden, followed by Chattogram and Rajshahi. The projections assume no further adaptation measures and that the link between temperature and preterm birth risk stays consistent with current evidence.
Dr Ummay Hafsa Mazumder, medical officer at Cumilla Sadar South Health Complex, said heavy sweating could cause significant electrolyte loss, with serious complications for mother and child. Heat exposure can cause dehydration, reduce blood flow to the placenta, trigger inflammation and activate pathways that may initiate labour, she said. Poverty, nutritional anaemia, strenuous work, limited antenatal care and inadequate cooling worsen the risks, and poorly ventilated homes can increase exposure even indoors.
Calls for action
In 2024, the Directorate General of Health Services and UNICEF introduced national guidelines to protect pregnant women and children from heat-related health risks. The study noted that heat protection has yet to be systematically integrated into routine maternal healthcare programmes. It recommends adding heat-risk information to antenatal care, strengthening community-based services, improving access to safe drinking water and cooling, and expanding early-warning systems.
Lead author Dr Joanne Bentley-McKune, a senior research analyst at ZCA, said Bangladesh had contributed little to historical emissions but was disproportionately affected by extreme weather. Adaptation alone could prevent only some of the additional cases, she said, making it essential to limit global warming.
Prof Dr Iqbal Kabir, director of the Center for Climate Change and Public Health, called the findings a "wake-up call". He urged heat-risk screening and counselling during antenatal visits, better training and equipment for frontline health workers, and safe, cool environments for vulnerable communities.