Higher temperatures may put pregnant women at an increased risk of developing gestational diabetes, a new study warns.
Researchers from St Michael's Hospital in Canada found that the prevalence of gestational diabetes increased from 4.6 per cent to 7.7 per cent among those women who were exposed to hot average temperatures (above 24 degrees Celsius).
They examined 5,55,911 births in about 3,96,828 women over a 12-year period. All the women studied lived in the Greater Toronto Area. However, some were pregnant when the average temperature was warmer, and some when it was cooler.
Researchers looked at the relationship between the average 30-day air temperature prior to the time of gestational diabetes screening in the second trimester, and the likelihood of gestational diabetes diagnosis.
The prevalence of gestational diabetes was 4.6 per cent among women exposed to extremely cold average temperatures (equal to or below minus 10 degrees Celsius) in the 30-day period prior to being screened for gestational diabetes.
It increased to 7.7 per cent among those exposed to hot average temperatures, researchers said.
They also found that for every 10 degree Celsius rise in temperature, women were six to nine per cent more likely to develop gestational diabetes.
"Many would think that in warmer temperatures, women are outside and more active, which would help limit the weight gain in pregnancy that predisposes a woman to gestational diabetes," said Gillian Booth from St Michael's Hospital.
"However, it fits a pattern we expected from new studies showing that cold exposure can improve your sensitivity to insulin, by turning on a protective type of fat called brown adipose tissue," Booth said.
The study was published in the Canadian Medical Association Journal.