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Extreme heat during April 2024 was associated with an estimated 5,515 additional preterm births in Bangladesh, representing an 11.9% increase compared with a typical April, according to a new study by international research organisation Zero Carbon Analytics (ZCA).
The study found that human-induced climate change contributed to 1,479 of these premature births by intensifying the heatwave.
The April 2024 heat event was made approximately 45 times more likely by human-caused climate change, according to World Weather Attribution.
The heatwave resulted in around 19 additional preterm births per 1,000 deliveries, the highest rate among the three countries examined — Bangladesh, India and the Philippines.
Bangladesh already has one of the world’s highest preterm birth rates. An estimated 16.2% of babies born in the country in 2020 were premature, compared with the South Asian average of 13.2%.
A preterm birth is defined as the delivery of a baby before completing 37 weeks of pregnancy. It is the leading cause of neonatal mortality worldwide, while premature babies also face higher risks of long-term physical and neurodevelopmental complications.
Dhaka, Chattogram account for 47% of cases
The impact of extreme heat was uneven across the country, with Dhaka and Chattogram divisions together accounting for 47% of the estimated 5,515 additional preterm births.
Mymensingh experienced the sharpest temperature increase, with April 2024 temperatures averaging 3.59 degrees Celsius above the division’s usual April baseline.
Mymensingh also recorded the highest rate of excess preterm births, at 24 per 1,000 deliveries, while Sylhet recorded the lowest rate, at 16 per 1,000 births.
The estimated increase in preterm birth risk ranged from 10% to 15% across all divisions.
Risk may increase further by mid-century
The study warns that heat-related premature births could increase further as global temperatures rise.
Bangladesh could experience around 1,500 additional preterm births during an average April by mid-century (2041–2060), compared with the 1985–2014 climate baseline.
The projected range is between 630 and 2,900 cases.
April temperatures are expected to rise by around 1.1 degrees Celsius by then, with Dhaka projected to face the highest burden, followed by Chattogram and Rajshahi.
Call for stronger maternal healthcare
Pregnant women are particularly vulnerable to extreme heat, which can cause dehydration, reduce blood flow to the placenta and trigger biological processes that may lead to premature labour.
Dr Ummay Hafsa Mazumder, a medical officer at Cumilla Sadar South Health Complex, said excessive sweating could cause significant electrolyte loss, potentially leading to serious complications for both mothers and unborn babies.
The study highlights the need to integrate heat protection into routine maternal healthcare through stronger antenatal services, heat-risk counselling, improved access to cooling and hydration, and early-warning systems.
Prof Dr Iqbal Kabir, a climate and public health expert and director of the Center for Climate Change and Public Health, described the findings as a wake-up call for Bangladesh.
He stressed the importance of strengthening heat-risk screening during antenatal visits, equipping frontline health workers and ensuring access to safe, cool environments for vulnerable communities.
