Prolonged exposure to high ambient temperatures during pregnancy is associated with a significant increase in the risk of developing gestational diabetes. This relationship emerges from a new study led by IDIAPJGol researcher Laura Granés, which analyses primary care data from more than 150,000 pregnancies in the Barcelona metropolitan area over a twelve-year period.
The study is based on a time-series design that combines daily temperature data from the Meteorological Service of Catalonia with clinical records from the Information System for Research Development in Primary Care (SIDIAP) between 2011 and 2022. This methodology made it possible to analyse both the cumulative and delayed effects of temperature, an aspect that has been little explored so far in relation to gestational diabetes.
Cumulative effects of heat
The research shows that cumulative exposure over 30 consecutive days to average temperatures around 21–23 °C (an average that also includes nighttime temperatures) may double the risk of being diagnosed with gestational diabetes. The results highlight that not only isolated episodes of extreme heat, but also prolonged periods of high temperatures, may have a significant impact on maternal health.
According to the study’s lead researcher, Laura Granés, “the impact of heat does not necessarily occur on the same day, but after continuous exposure over several weeks.” These findings are consistent with previous evidence suggesting that exposure to high temperatures may reduce insulin sensitivity and slow glucose metabolism, which contributes to increased blood sugar levels.
Social inequalities
The study also explored the role of socioeconomic context in the relationship between temperature and gestational diabetes. Researchers observed that women living in neighbourhoods with lower socioeconomic status appear to be more vulnerable to the effects of heat.
“Although the association between higher temperatures and gestational diabetes is detected across several groups, the trend is more pronounced in more disadvantaged environments,” Granés notes. According to the research team, factors such as housing conditions, type of employment, or a lower capacity to protect oneself from heat could explain these differences.
Strengthening prevention
The researchers note that these results reinforce the need to increase awareness about the risks of heat exposure during pregnancy. “Preventive information and recommendations aimed at pregnant women should be strengthened, especially during periods of heatwaves,” Granés adds.
The study highlights the importance of incorporating a climate change perspective into public health strategies and pregnancy monitoring protocols, with particular attention to the most socially vulnerable groups.
Article reference
Granés, L., Palomar-Cros, A., Espiell, A. et al. Cumulative daily exposure to high temperature increases gestational diabetes risk. Nat. Health (2026). https://doi.org/10.1038/s44360-026-00077-2
