The cause of global warming is (mainly) carbon dioxide in the atmosphere that absorbs sunlight and solar radiation, which would normally escape into space. This causes the planet to get hotter and is known as the greenhouse effect or climate change.
Substantial number of women affected
The potential effects of global climate change and the rise in air temperature may increase a woman's risk of developing gestational diabetes during pregnancy, a new study suggests.
Mothers-to-be in very cold climes are less likely to develop diabetes during pregnancy than women exposed to hotter temperatures, researchers say.
The report was published online in the CMAJ (Canadian Medical Association Journal).
Changes in temperature may only lead to a small increase in the risk of gestational diabetes, but the number of women affected may be substantial, said Dr Gillian Booth, scientist at the Li Ka Shing Knowledge Institute at St. Michael's Hospital in Toronto.
No direct cause-and-effect relationship
"Temperature and risk of diabetes is a hot topic," said Dr Joel Zonszein, director of the clinical diabetes centre at Montefiore Medical Center in New York City.
However, the study doesn't show a direct cause-and-effect relationship, and Zonszein cautioned that it's too soon to consider the findings definitive.
Booth explained that gestational diabetes in women develops in the second trimester of pregnancy and is usually temporary. Women are screened for it at 24 to 28 weeks of pregnancy.
If there is a connection between temperature and gestational diabetes risk, cells called brown fat might help explain it.
According to Zonszein, "Brown fat cells are cells that – instead of storing energy – burn energy."
Booth speculated that extreme cold triggers activity of brown fat, thus controlling weight gain. It might even lead to weight loss, improving blood-sugar levels, she noted.
However, Zonszein said that many environmental factors – such as excessive food intake, sugary drinks, inactivity, stress and lack of sleep – can cause gestational diabetes in women genetically susceptible to the disease.
"Genetic factors are very important," he said, "and they are affected by many environmental factors, probably temperature is one more."
Lowering the odds
Besides a healthy diet and physical activity to avoid excess weight, controlling temperature might be something women can do for a healthier pregnancy, Booth suggested.
"For example, turning down the thermostat and getting outside in the winter, or using air conditioning in summer, and avoiding excess layers in hot weather may help to lower the risk of gestational diabetes," she said.