The increased frequency and intensity of heatwaves is resulting in preterm and early-term labor, a study has found. According to a new multi-institutional study published JAMA Network Open, premature births are increasing due to hot weather conditions to intense and prolonged heatwaves. The researchers analysed 5.3 crore births across the 50 largest metropolitan areas in the US over a 25-year period (1993-2017) in terms of daily counts of preterm and early-term births.