During pregnancy, some women have higher than normal levels of glucose in their bloodstream, and their bodies struggle to produce enough insulin to process it all.
The study, published on thebmj.com, examined the effect of these so-called low-risk lifestyle factors on pregnancies in an attempt to calculate how many cases could be prevented through adherence to healthy living guidelines.
The Centers for Disease Control and Prevention (CDC) state that gestational diabetes affects between 2-10% of pregnancies in the US. It occurs when the body is unable to produce enough insulin to cope with the increased demands of pregnancy.
Although gestational diabetes goes away after the mother has given birth, women who have had gestational diabetes have a 35-60% chance of developing diabetes in the following 10-20 years.
As well as having future health implications for the mother, a high glucose concentration in the blood is believed to cause the malformation of embryos. Children born after gestational diabetes are more likely to have birth defects and could be at a higher risk of becoming obese or intolerant to glucose when growing up.
"Identification of behaviors and habits that could protect women from gestational diabetes would be an important step towards reducing the burden of this condition," writes Associate Professor Sara Meltzer of McGill University, Canada, in an editorial accompanying the study.
The benefits of the 'low-risk' lifestyle factors
The researchers analyzed data for over 14,000 healthy women in the US participating in the Nurses' Health Study II, from 1989-2001. The weights, diets, levels of physical activity and smoking statuses for the participants were observed, along with cases of gestational diabetes that were validated by medical records from a previous study.
A total of 823 cases of gestational diabetes were reported. The biggest risk factor was found to be being overweight - having a BMI over 25 prior to pregnancy. Women whose BMI was over 33 prior to pregnancy were found to be more than four times as likely to develop gestational diabetes than other participants.
Participants who had a combination of three of the previously identified low-risk lifestyle factors - not smoking, regularly exercising, maintaining a healthy weight - were 41% less likely to develop gestational diabetes than other pregnant women. If they began pregnancy at normal weight, this figure increased to 52%.
The researchers also found that even those who were overweight or obese before pregnancy derived benefit from not smoking, regularly exercising and eating healthily. Those who followed all four of the healthy living criteria were 83% less likely to develop gestational diabetes than those who followed none of them.
Using a mathematical formula, the researchers calculated that an estimated 48% of all gestational diabetes pregnancies could have been prevented if women followed all four of the low-risk lifestyle guidelines - not smoking, eating healthily, exercising regularly and maintaining a healthy weight - prior to pregnancy.
'An opportunity to change'
The authors acknowledge that their data sample was not wholly representative of the population, as all of the participants were health professionals. "The prevalence of overweight or [obesity] among US women of reproductive age was about 60% in the National Health and Nutrition Examination Survey 2007-08 but only 27% in the present study," they write.
In her editorial, Meltzer states that it is important for future research to determine whether "the apparent effect of lifestyle is the same in other ethnic groups or in populations that are less well educated about health," having noted that the participants were predominantly white and all health care workers.
Despite this limitation, the authors hope that their findings could motivate women who may be planning a pregnancy to make positive lifestyle changes:
"Although it is always challenging to change behavior/lifestyle, the time before and during pregnancy could represent an opportunity to change diet and lifestyle as these women might be particularly motivated to adhere to advice to improve pregnancy and/or birth outcomes."
Just as pregnancy often heralds the beginning of a new life for a mother, so too could it herald the beginning of a new, healthier lifestyle. Although lifestyle changes are always tricky, this study has identified some health benefits that could be just the incentive some people need.
Recently, Medical News Today reported on a study that found maternal iron intake could be linked to a child's risk of autism.