Exposure to extreme heat waves during the last week of gestation might cause premature birth defined as birth before 37 weeks of gestation. A cohort study in California with 1,967,300 mothers showed consistent results with higher numbers of preterm birth in women who experienced an extreme heat episode in the week prior to labor. The publication „Extreme heat episodes and risk of preterm birth in California, 2005-2013“ describes a large population-based cohort study, in…