Gestational diabetes is a birth complication affecting millions of women worldwide. New research examines the link between air temperature and the risk of developing this condition.
New research suggests that hotter outdoor air temperatures may significantly increase a mother’s risk of GD during her pregnancy.
Gestational diabetes (GD) is a temporary form of diabetes that affects some women during pregnancy. These future mothers often have no history of diabetes prior to getting pregnant, but their blood sugar increases by the time they are halfway through their pregnancy.
In 2014, the Centers for Disease Control and Prevention (CDC) reported that in the United States, as many as 9.2 percent of pregnant women may be affected by GD. Worldwide, around 1 in 7 births are affected by this complication.
GD occurs when the hormones in the placenta trigger insulin resistance, meaning that healthy blood sugar levels cannot be maintained.
Sensitivity to insulin is known to be improved by exposure to cold temperatures, during which the body produces more heat to keep itself warm. However, could it be that outside air temperatures have a larger impact on the risk of developing GD?
Researchers from St. Michael’s Hospital, the Institute for Clinical Evaluative Sciences (ICES), Mount Sinai Hospital, and the University of Toronto – all in Ontario, in Canada – set out to explore the connection between outdoor air temperature and the risk of GD.
The findings were published in CMAJ.
Each 10°C temperature increase raises risk of GD by 6 to 9 percent
The study examined 555,911 births from 396,828 women over a period of 12 years, from 2002 to 2014.
The women were 31 years old on average, and lived in the Greater Toronto Area. Approximately half of the mothers were not born in Canada.
Extremely cold outdoor temperatures were defined as an average of 10°C or less, and hot temperatures as 24°C on average.
The women were exposed to these different temperatures for 30 days before being screened for GD.
GD occurred in 4.6 percent of the women that had been exposed to extremely cold temperatures, but this number jumped to 7.7 percent for the women who had been exposed to hot temperatures.
Furthermore, each 10°C increase in temperature correlated with a 1.06 times higher risk of GD. A similar trend was found when the temperature increased between two pregnancies in the same mother.
“By further limiting our analysis to pregnancies within the same woman, we controlled for a whole number of factors,” says co-lead author Dr. Joel Ray, a researcher at St. Michael’s and ICES. “Doing so allowed us to eliminate factors like ethnicity, income, activity, and eating habits that would differ between two different women.”
Lead author Dr. Gillian Booth, a researcher at St. Michael’s and ICES, reports on the findings: