Exposure to extreme heat is associated with an increased risk of babies being born with low birth weight, according to a study involving researchers from Adelaide University, as announced on Apr. 1.
The study highlights concerns about the impact of rising temperatures on maternal and infant health, especially in regions already facing socioeconomic challenges. Researchers say that climate change may further increase these risks in the coming decades.
The research, published in BMC Medicine, analyzed health data from over 85,000 mothers and babies in Pakistan. The team examined ten years of birth records alongside monthly temperature data to determine how heat exposure affects infant size at birth. Associate Professor Zohra Lassi from Adelaide University's Robinson Research Institute said, "We found pregnant women in this study were at a higher risk of delivering infants of a low birth weight following exposure to extreme temperatures." She added that the risk was up to 70 percent higher in some areas more vulnerable due to hotter climates and greater socioeconomic disadvantage.
The findings show that eighteen percent of babies had low birth weight—defined as weighing less than 2.5 kilograms or being described as smaller than average at birth. Up to thirteen percent of these cases were attributed directly to hot weather conditions. The burden is projected to rise by eight to ten percent by the 2060s due to ongoing climate change.
Associate Professor Lassi said, "Low birth weight is already a major neonatal health issue in Pakistan, leading to neonatal mortality and impaired long-term health problems such as stunted growth or cognitive defects." Lead author Hira Fatima from the HEAL Global Research Centre at the University of Canberra noted that heat interacts with existing issues like poverty and limited healthcare access: "In Pakistan, heat does not occur in isolation...climate change can deepen risks for mothers and newborns in ways that are far from equal." Fatima also stated, "Our study shows that these structural disadvantages are already shaping who is most at risk of heat-related low birth weight."
To identify high-risk regions within Pakistan, researchers created a heat vulnerability index highlighting Southern Punjab, northern Sindh and Baluchistan as particularly susceptible provinces. Dr Fatima said effective adaptation requires more than just warnings: "Our findings show that climate adaptation in Pakistan cannot stop at heat warnings alone. It needs to include stronger maternal health services, better protection for vulnerable pregnant women, and targeted support for the districts facing the greatest heat risk." Associate Professor Lassi called for urgent interventions: "Interventions designed to mitigate the effects of climate change, enhance access to essential healthcare services, and promote sustainable development are urgently required...This includes public health programs...along with much-needed investment in improvements to health infrastructure."
While based on Pakistani data, researchers believe their results have wider significance for countries expecting hotter climates worldwide. Associate Professor Lassi concluded: "These insights are highly relevant for other countries facing rising temperatures...and highlight the need for public health preparedness and climate-adapted maternal care strategies."
