The prevalence of gestational diabetes was 4.6 per cent among women exposed to extremely cold average temperatures (equal to or below -10 C) in the 30-day period prior to being screened for gestational diabetes, and increased to 7.7 percent among those exposed to hot average temperatures (above 24 C). The study also found that for every 10-degree Celsius rise in temperature, women were 6 to 9 percent more likely to develop gestational diabetes.