Cold weather reduces pregnancy diabetes risk

15^th May 2017 - Colder weather and outside temperatures can reduce the risk of developing diabetes in pregnancy, known as gestational diabetes.

According to Canadian research the outdoor air temperature has a direct link to the risk of gestational diabetes, and for every 10C rise in temperature, women are 6% – 9% more likely to develop the condition.

Gestational diabetes

Gestational diabetes is a new diagnosis of high blood sugar levels, most often developing in the second trimester of pregnancy. It is usually temporary and disappears after giving birth.

It happens when a mother's body is unable to produce enough insulin to control blood sugar levels.

Gestational diabetes can cause problems for mother and baby but the risk is reduced if it's detected and well managed.

The study

Researchers at St. Michael's Hospital and the Institute for Clinical Evaluative Sciences in Toronto looked at 555,911 births among 396,828 women living in the Greater Toronto Area, where there are wide seasonal fluctuations in temperature.

The study covered the 12-year period between 2002 and 2014 so some women were pregnant when it was warmer, and some when it was cooler.

Researchers looked at the relationship between the average 30-day temperature prior to the time of screening in the second trimester - usually the 27th week of pregnancy - and the likelihood of a diagnosis of gestational diabetes.

The average age of the mothers when giving birth was 31 years, and almost half of the births were to women born outside of Canada.

Findings

Researchers observed a direct relation between outdoor temperature and the risk of gestational diabetes.

The prevalence of gestational diabetes was 4.6% among women exposed to extremely cold average temperatures (-10C or colder) in the 30-day period prior to being screened for gestational diabetes, and increased to 7.7% among those exposed to hot average temperatures (24C or higher).

In addition, where a woman was born also played a part. Women born in cooler climates, including Canada and the United States, who were exposed to cold temperatures during the 30-day period before screening had a gestational diabetes rate of 3.6%, while those exposed to hot temperatures had a rate of 6.3%. In comparison, women who were born in hot climates, including South Asia, Africa and the Middle East, had rates of gestational diabetes of 7.7% and 11.8%, respectively.

The findings have been published online in the Canadian Medical Association Journal.

Possible reasons

The reason temperature may affect a woman's chances of getting gestational diabetes may be down to the way in which we make different types of fat.

Exposure to the cold can improve sensitivity to insulin, by turning on a protective type of fat called brown adipose tissue. It has the ability to generate heat and helps the body acclimatise to cold, which is known to improve insulin sensitivity.

Future cases

The authors suggest that the forecast rise in global temperatures by 2050 may lead to a substantial increase in the number of cases of gestational diabetes worldwide.

In the meantime they suggest that lowering your home thermostat or spending more time outdoors in cooler weather may reduce a woman’s risk of gestational diabetes.

Limitations

The study lacked data on pre-pregnancy body mass index (BMI) for most women, also there was no information on physical activity or diet during the study period, all of which can have an impact on gestational diabetes.