April heat triggers 5,515 preterm births: Study

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

Dhaka and Chattogram divisions together accounting for 47 percent of the estimated 5,515 excess preterm births, the report said adding that human-caused climate change had made the April 2024 heat event around 45 times more likely.

Bangladesh already has the world's highest national average preterm birth rate. In 2020, an estimated 16.2 per cent of babies born in the country were premature, compared with 13.2 percent across South Asia.

It said 1,479 premature births were attributable to the additional warming caused by human-induced climate change, the study found

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.

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.

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.

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.

123 16.2pc babies born were premature in 2020 compared with 13.2pc across South Asia 123

The impact of extreme heat was uneven across the country, 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.

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.

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.

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.

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