A growing body of research is strengthening the link between climate change and maternal health, with a new study finding that exposure to extreme heat significantly increases the likelihood of babies being born underweight.
The research, led by scientists from the University of Adelaide and published in BMC Medicine, analyzed data from more than 85,000 mothers and infants in Pakistan over a ten-year period. The findings show that pregnant women exposed to higher temperatures face a markedly increased risk of delivering low birth weight babies, defined as weighing less than 2.5 kilograms.
According to the study, the risk of low birth weight rose by up to 70 percent in some regions most affected by extreme heat. Researchers estimate that up to 13 percent of such cases can already be attributed to high temperatures, with projections suggesting this burden could rise by an additional 8 to 10 percent by the 2060s as global warming intensifies.
Low birth weight is a critical global health issue, often associated with increased neonatal mortality, developmental delays, and long-term conditions such as stunted growth and cognitive impairment. The study highlights how climate-related heat exposure compounds existing challenges, including poverty, limited access to healthcare, and poor nutrition.
Researchers also identified geographic disparities, with regions such as southern Punjab, northern Sindh, and Baluchistan facing the highest vulnerability. These findings underscore how climate change disproportionately impacts already at-risk populations, amplifying health inequalities.
Experts warn that the implications extend far beyond a single country. As global temperatures continue to rise and heatwaves become more frequent, similar risks are expected to emerge in other regions, including developed nations.
The study calls for urgent action, including stronger maternal healthcare systems, targeted support for vulnerable communities, and climate adaptation strategies designed to protect pregnant women during extreme heat events.
As climate change accelerates, the research adds to mounting evidence that its consequences are not only environmental but deeply human, affecting health outcomes from the earliest stages of life.
District-level spatial patterns of the heat vulnerability index of low birth weight associated with heat. © Adelaide University and University of Canberra
