A study led by researcher Laura Granés, of the Jordi Gol Institute for Primary Care Research (IDIAPJGol), analyzed primary care data from more than 150,000 pregnancies in the Barcelona metropolitan area over 12 years, between 2011 and 2022.
The results show that cumulative exposure over 30 straight days to average temperatures of between 21 and 23 degrees Celsius — an average that also includes nighttime temperatures — can double the risk of a pregnant woman being diagnosed with gestational diabetes. This isn't about a single day's heat spike, but the effect of sustained high temperatures over several weeks.
The study also found that pregnant women living in lower socioeconomic neighborhoods are more vulnerable to the effects of heat, which the authors say reinforces the need to consider social and environmental context, not just clinical factors, when preventing gestational diabetes.