Researchers found Canadian women were more likely to
be diagnosed with gestational diabetes if they were
exposed to higher average outdoor temperatures
during pregnancy, compared to women who were
pregnant in cooler periods.
Lead author Dr. Gillian Booth, of St. Michaelís
Hospital and the Institute for Clinical Evaluative
Sciences in Toronto and colleagues write in the
Canadian Medical Association Journal that research
suggests exposure to the cold increases people's
sensitivity to the hormone insulin.
People with type 2 diabetes and gestational diabetes
don't respond to or don't produce enough of the
hormone, which helps the body convert sugar into
For the new study, the researchers analyzed data
from 396,828 women and their 555,911 deliveries in
the Greater Toronto Area from 2002 to 2014.
They identified all births in the Greater Toronto
Area from 2002 to 2014 using administrative health
Generalized estimating equations were used to
examine the relation between the mean 30-day outdoor
air temperature before the time of gestational
diabetes mellitus screening and the likelihood of
diagnosis of gestational diabetes mellitus based on
a validated algorithm using hospital records and
physician service claims.
The researchers compared the risk of developing
diabetes during pregnancy among women exposed to an
average outdoor temperature of at most -10 degrees
Celsius (C), or 14 degrees Fahrenheit (F), during
the 30 days before their gestational diabetes test
to women exposed to at least 24 degrees C, about 75
degrees F, before their tests.
The prevalence of gestational diabetes among women
exposed to colder outdoor temperatures was 4.6
percent, compared to 7.7 percent among women exposed
to warmer temperatures.
But the new study can't prove that warmer
temperatures cause women to have gestational
diabetes. For example, there may be other seasonal
factors influencing the risk of gestational diabetes
like fluctuating vitamin D levels, said Dr. Kathryn
Drennan, a maternal fetal medicine physician at the
University of Rochester Medical Center in New York,
who wasn't involved with the new study.
For more information
Influence of environmental temperature on risk of