Europe's recent historic heatwave has brought more than discomfort. A new study in the journal Environment International reveals extreme heat drives premature births.
Analyzing 36.6 million summer births across 13 countries from 1979 to 2019, researchers found heat triggers earlier labor by raising body temperature, causing dehydration, and reducing blood flow to the placenta.
On moderate heat days, preterm birth risk rises 2.8%; on extreme days, it jumps to 3.8%. Spain leads with 1,080 preterm births per million, followed by Italy (974) and Estonia (814). Switzerland had the lowest rate at 628 per million.
Vulnerable populations-young, single mothers with lower education-face greater risks. The highest sensitivity period is weeks 31 to 40 of gestation.
Europe's heatwave saw temperatures 10-15°C above normal, with Mora, Portugal hitting 40.3°C on May 27.