A nationwide study has found that prolonged exposure to extreme heat during pregnancy significantly increases the risk of adverse birth outcomes, with women in India’s mountainous regions—including Northeastern states such as Meghalaya, Nagaland and parts of Assam—emerging among the most vulnerable despite traditionally cooler climates.
Published in the peer-reviewed journal Environmental Research Communications, the study analysed 209,266 births recorded across India between 2015 and 2020. Researchers matched each pregnancy with local heat conditions using the India Heat Index, measuring consecutive “sweltering” days rather than average temperatures. The findings showed that every additional consecutive day of extreme heat during pregnancy increased the odds of delivering a low-birth-weight baby by about one per cent. Heat exposure during the first trimester was associated with a higher risk of preterm birth, while second-trimester exposure was linked to low birth weight.
Led by researchers from the University of Queensland–IIT Delhi Academy of Research (UQIDAR), IIT Delhi and the University of Queensland, with collaborators from UNSW Sydney, the University of Exeter and Korea University, the study suggests that women in mountainous regions may be more susceptible because they are less acclimatised to prolonged heat.
Lead author Vineetha Vincent said extreme heat should no longer be viewed as merely a background environmental condition during pregnancy, warning that longer and more frequent heatwaves driven by climate change could disproportionately affect vulnerable mothers. Co-author Nicholas J. Osborne said India’s heat action plans should explicitly recognise pregnant women as a priority group and include practical interventions such as cooling measures, hydration support and strengthened antenatal care.
The findings are particularly relevant for Guwahati and the wider Assam region, where rising summer temperatures and prolonged humid conditions have become increasingly common. Public health experts say the study could boost demand for maternal healthcare services, cooling solutions, hydration products and heat-awareness campaigns, while prompting hospitals, healthcare providers and government agencies to strengthen preparedness for protecting pregnant women during extended heatwave periods.