Climate change takes toll on pregnancies
Human-induced climate change is estimated to have contributed to nearly 1,500 additional preterm births in Bangladesh during the extreme heatwave of April 2024, highlighting the growing threat of rising temperatures to maternal and newborn health.
A new analysis by Zero Carbon Analytics (ZCA), an international research group specialising in climate change and the energy transition, estimates that 1,479 premature births during the month could have been avoided in the absence of additional warming caused by human activities.
The April 2024 heat event itself was made around 45 times more likely by human-induced climate change, according to World Weather Attribution.
In a separate assessment, ZCA estimated that the heatwave was associated with approximately 5,515 excess preterm births compared with the average for April during the 1991-2020 period.
This represented an 11.9 per cent increase, equivalent to around 19 additional preterm births per 1,000 deliveries – the highest rate among the three countries examined in the study.
The findings underscore the mounting threat that climate-driven extreme heat poses to pregnant women and newborns in Bangladesh, which already has one of the highest rates of premature births worldwide.
Bangladesh recorded an estimated preterm birth rate of 16.2 per cent in 2020, the highest national average globally, while the South Asian regional rate stood at 13.2 per cent.
A preterm birth is defined as a delivery before 37 completed weeks of pregnancy.
It is the leading cause of neonatal mortality worldwide, with premature babies facing greater risks of death as well as long-term physical, neurodevelopmental and socioeconomic complications.
Dhaka, Chittagong bear nearly half the burden
The impact of the April 2024 heatwave varied considerably across the country, with Dhaka and Chittagong, the two most populous divisions, accounting for 47 per cent of the estimated 5,515 excess preterm births.
Mymensingh, however, emerged as a particularly vulnerable area in terms of rising temperatures and the rate of additional premature births.
Temperatures in the division averaged 3.59 degrees Celsius above its usual April baseline, the largest increase recorded among the country’s eight divisions.
The estimated increase in preterm birth risk ranged between 10 and 15 per cent across all divisions.
Mymensingh recorded the highest rate of excess preterm births, at 24 per 1,000 deliveries, despite ranking sixth among the eight divisions in the total number of additional cases.
Sylhet recorded the lowest rate, at 16 additional preterm births per 1,000 deliveries.
The findings indicate that national averages alone cannot adequately reflect the health consequences of extreme heat.
While densely populated divisions account for larger numbers of cases, less populous areas may experience sharper increases in the risk of premature births.
Another 1,500 excess cases projected by mid-century
The analysis warns that the burden of heat-related premature births in Bangladesh could grow as global temperatures continue to rise.
Under moderate and higher future-warming scenarios, the country could experience approximately 1,500 excess preterm births during a typical April by mid-century (2041-2060), compared with the 1985-2014 climate baseline.
The projected range is between 630 and 2,900 additional cases, reflecting an estimated 1.1-degree Celsius rise in April temperatures by the middle of the century.
Dhaka Division is expected to face the largest burden, followed by Chittagong and Rajshahi.
The projections assume that no additional adaptation measures are introduced and that the relationship between temperature and premature birth risk remains consistent with current evidence. They also take account of projected changes in the number of births.
Heat protection needed in maternal healthcare
Pregnant women are particularly vulnerable to extreme heat because of the additional physiological demands of pregnancy.
Exposure to high temperatures can cause dehydration, reduce blood flow to the placenta, trigger inflammation and activate biological pathways that may initiate labour.
Medical Officer of Cumilla Sadar South Health Complex Dr Ummay Hafsa Mazumde said intense heat could pose serious health risks to pregnant women.
She said excessive sweating could lead to substantial electrolyte loss, potentially causing serious complications for both mothers and their unborn babies.
The risks are further aggravated by poverty, nutritional anaemia, physically demanding work, limited access to antenatal care and inadequate cooling facilities.
Poorly ventilated homes and heat-trapping construction materials can also expose pregnant women to dangerous temperatures even when they remain indoors.
Bangladesh has already taken an initiative to address the problem. In 2024, the Directorate General of Health Services, in collaboration with UNICEF, introduced national guidelines specifically designed to protect children and pregnant women from heat stress, acknowledging the associated risk of premature births.
However, heat protection has yet to become a systematic part of routine maternal healthcare programmes.
The challenge now is to translate the guidelines into practical protection, particularly for pregnant women and newborns in communities facing the greatest exposure to extreme temperatures.
Integrating heat-risk information into antenatal services, strengthening community-based maternal healthcare, improving access to cooling and safe drinking water, and expanding heat early-warning systems could help reduce the risks.
The study also stresses the need to strengthen healthcare preparedness in divisions facing the largest overall burden while ensuring that areas experiencing the sharpest increases in risk receive adequate attention.
Dr Joanne Bentley-McKune, lead author of the report 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 the potentially lifelong health consequences associated with them.
“Bangladesh has contributed relatively little to the historical emissions driving climate change, yet [it is] disproportionately affected by climate-driven extreme weather compared with high-income, high-emitting countries, which also have more resources to adapt,” she said.
She said the estimates could help identify areas requiring greater healthcare capacity, adding that adaptation measures, including improved antenatal care and early-warning systems, should be prioritised.
However, she cautioned that such measures could prevent only part of the additional preterm birth burden caused by climate change, making it essential to limit further global warming.
Prof Dr Iqbal Kabir, a climate and public health expert and director of the Centre for Climate Change and Public Health, described the findings as a wake-up call for Bangladesh.
“These findings are a wake-up call for Bangladesh.
Extreme heat is an urgent public health threat for pregnant women and newborns in the country.
The estimated 5,515 excess preterm births during the April 2024 heat event highlight the need to integrate heat protection into maternal healthcare,” he said.
He called for stronger heat-risk screening and counselling through antenatal services, better-equipped frontline health workers, improved early-warning systems and access to safe, cool environments, particularly for vulnerable communities.
Protecting mothers and newborns from extreme heat, he said, required coordinated action across the healthcare system, climate policy and communities.
