Extreme heat conditions are causing more babies to be born underweight, according to a new study involving researchers at the University of Adelaide.
Collaborative study, published in bmc medicalHealth data from more than 85,000 mothers and babies in Pakistan were used to assess the impact of extreme heat on infant size.
“In this study we found that pregnant women exposed to extreme temperatures have a higher risk of giving birth to low birth weight babies,” said project lead Associate Professor Zohra Lassi, from the University of Adelaide’s Robinson Research Institute.
“This risk was as high as 70 percent in some areas of Pakistan, which are more vulnerable to adverse birth outcomes due to their warmer climate and greater socioeconomic disadvantage, among other factors.”
The researchers used a combination of ten years of birth data (2008-2017) and monthly average temperature exposure to determine the relationship between heat and birth weight.
Eighteen percent of infants were found to be low birth weight, defined as weighing less than 2.5 kg or smaller than average in size at birth.
13 percent of cases of low birth weight were attributed to hot weather conditions, with this burden projected to increase to approximately 8 to 10 percent by 2060 due to climate change.
“Low birth weight is already a major neonatal health issue in Pakistan, leading to neonatal mortality and long-term health problems such as stunted growth or cognitive impairment,” Associate Professor Lassi said.
Pakistan has experienced extreme heat, drought and flooding in recent decades, raising concerns about the health and well-being of mothers and infants.
“In Pakistan, heat does not occur in isolation. It interacts with existing challenges such as poverty, limited health care access, poor air quality and maternal undernutrition, meaning that climate change could deepen the threats to mothers and newborns, which are not the same,” said lead author Hira Fatima, a postdoctoral research fellow at the HEAL Global Research Center at the University of Canberra.
“Our study shows that these structural disadvantages are already shaping who is most at risk for heat-related low birth weight.”
As part of this study, researchers created a heat vulnerability index to identify provinces at greater risk of low birth weight associated with hot temperatures, with southern Punjab, northern Sindh and Balochistan considered the most vulnerable.
Dr. Fatima said, “Our findings show that climate adaptation in Pakistan cannot be limited to heat warnings alone. It needs to include stronger maternal health services, better protection for vulnerable pregnant women, and targeted support for districts facing the greatest heat risk.”
“There is an urgent need for interventions designed to mitigate the impacts of climate change, increase access to essential health services and promote sustainable development,” said Associate Professor Lassi.
“This includes public health programs to educate and help pregnant women cope with extreme heat events, as well as much-needed investments to improve health infrastructure.”
While the study focused on data from Pakistan, researchers believe the findings have important implications for many other countries preparing for extreme heat in the future, where global average temperatures are expected to remain at record lows.
“These insights are highly relevant to other countries facing rising temperatures, including Australia, and highlight the need for public health preparedness and climate-adapted maternal care strategies,” Associate Professor Lassi said.
