Heatwave linked to 5,515 excess preterm births in 2024: Report

Extreme heat during April 2024 was associated with an estimated 5,515 excess preterm births in Bangladesh, an 11.9% increase compared with a typical April, according to a new study by international research organisation Zero Carbon Analytics (ZCA).

Of these, 1,479 premature births were attributable to the additional warming caused by human-induced climate change, the study found. The report, released on Monday, said human-caused climate change had made the April 2024 heat event around 45 times more likely.

The heatwave resulted in approximately 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. In 2020, an estimated 16.2% of babies born in the country were premature, compared with 13.2% across South Asia.

A preterm birth is defined as the birth of a baby before 37 completed weeks of pregnancy. It is the leading cause of neonatal mortality globally, 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 excess preterm births.

Mymensingh, however, experienced the sharpest rise in temperature. During April 2024, temperatures in the division averaged 3.59 degrees Celsius above the usual April baseline, the highest increase among the country's eight divisions.

Mymensingh also recorded the highest rate of excess preterm births, at 24 per 1,000 deliveries, despite ranking sixth in the total number of cases. Sylhet recorded the lowest rate, at 16 per 1,000 births.

The estimated increase in preterm birth risk ranged between 10 and 15 percent across all divisions, highlighting the widespread impact of extreme heat on maternal health.

Risk may increase further by mid-century

The study warns that the burden of heat-related premature births could grow as global temperatures continue to rise.

Bangladesh could experience around 1,500 excess preterm births during an average April by mid-century (2041-2060), compared with the 1985-2014 climate baseline, the projections suggest. The estimated range is between 630 and 2,900 cases.

April temperatures are projected to rise by around 1.1 degrees Celsius by then. Dhaka is expected to face the highest burden, followed by Chattogram and Rajshahi divisions.

The projections assume that no additional adaptation measures are introduced and that the relationship between temperature and preterm birth risk remains consistent with current evidence.

Dr Ummay Hafsa Mazumder, medical officer at Cumilla Sadar South Health Complex, said extreme heat could pose serious health risks to pregnant women.

Excessive sweating can cause significant loss of electrolytes, potentially leading to serious complications for both the mother and her unborn child, she said.

Heat exposure during pregnancy can cause dehydration, reduce blood flow to the placenta, trigger inflammation and activate biological pathways that may initiate labour.

The risks are further aggravated by poverty, nutritional anaemia, strenuous physical work, limited access to antenatal care and inadequate cooling facilities. Poorly ventilated homes can also increase heat exposure, even when women remain indoors.

Call for heat protection in maternal healthcare

In 2024, the Directorate General of Health Services, in collaboration with UNICEF, introduced national guidelines to protect pregnant women and children from heat-related health risks.

However, heat protection has yet to be systematically integrated into routine maternal healthcare programmes, the study noted.

It recommends incorporating heat-risk information into antenatal care, strengthening community-based maternal health services, improving access to safe drinking water and cooling facilities, and expanding heat early-warning systems.

Dr Joanne Bentley-McKune, lead author of the study and senior research analyst at Zero Carbon Analytics, said climate change was making extreme heat more frequent and intense, increasing the risk of premature births and potentially lifelong health complications.

Read More

Bangladesh braces for warmer September as 2–3 heatwaves forecast

She said Bangladesh had contributed relatively little to the historical emissions driving climate change but was disproportionately affected by climate-related extreme weather.

The findings could help identify areas where greater healthcare capacity is needed, with better antenatal care and early-warning systems among the priorities, she said.

However, adaptation measures alone could prevent only some of the additional preterm births associated with climate change, making it essential to limit further global warming.

Prof Dr Iqbal Kabir, 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 called for stronger heat-risk screening and counselling during antenatal visits, better training and equipment for frontline health workers, improved early-warning systems and access to safe, cool environments, particularly for vulnerable communities.

Protecting mothers and newborns from extreme heat requires coordinated action across the healthcare system, climate policy and local communities, he added.