There is no evidence that a low glycemic diet can help prevent pregnancy-related diabetes, a recent review of several studies has found.
Gestational diabetes mellitus or pregnancy-related diabetes is a metabolic disorder affecting up to 14 percent people worldwide.
And, as this condition results in increased health risks for mothers and their babies, therefore researchers are searching for a means to prevent the disorder.
"The main implications of our research are suggestions for more high quality, long-term trials in healthy pregnant women, with larger sample sizes and reporting all clinically relevant outcomes, to address dietary issues more thoroughly and provide more conclusive results," said lead review author Joanna Tieu.
"Our results suggest that a low glycemic index diet may be a benefit to mother and child, however. This is because low glycemic index diets - such as fresh fruits and vegetables and unprocessed whole-grain foods - tend to slow down the digestion of food. Slow digestion allows the body to better adjust to the load of sugar coming in after a meal. While our results were promising, the evidence is not sufficient to recommend changes in clinical practices, because of the limited number of trials," said Tieu.
The review authors focused on three eligible studies including only 107 women living in the United States, Australia and the United Kingdom.
It's not yet understood what exactly causes gestational diabetes, but it is suspected that hormones from the placenta block the action of the mother's insulin. Without enough insulin, sugar (glucose) cannot enter cells, where it is needed to fuel cell activity. Instead, sugars build up in the bloodstream, causing hyperglycemia.
These excess sugars and other nutrients flow through the placenta and into the baby's cells, giving the baby more energy than it needs to develop. Stored as fat, these excess sugars may cause the baby to grow quite large - more than 8.8 pounds - or greater than the 90th percentile, compared to other babies.
A baby with a large size may get wedged on the mother's pubic bone during delivery, and the baby might be at risk for developing a number of health problems, including fractures or brachial plexus injuries, which can damage the network of nerves connecting the spine with the shoulder, arm and hand.
"Gestational diabetes also has been associated with spontaneous labor and premature birth. And children of women with gestational diabetes are at increased risk of obesity, glucose intolerance and diabetes in late adolescence and young adulthood," said Tieu.
Women with gestational diabetes are more prone to preeclampsia (hypertension) or placental abruption during pregnancy. Induced births or Caesarean sections are more common, adding even more health risks. These women also have an increased risk of developing diabetes in the future.
According to obstetrician Seth Brody, with Wake Medical Center in Raleigh, N.C., very large studies with longer follow-up are necessary to find out if dietary changes can alter significant health outcomes.
"If the difference in birth weight were significant enough to be reflected as a difference in birth injury rates, Caesarean delivery rates and the need for operative deliveries, then that difference is of clinical importance, as is studying rates of brachia plexus injuries, fractures or neonatal mortality." he said.
He added: "If a low glycemic diet altered the incidence of treatment for short- or long-term metabolic issues for either mom or baby, then those would be very important health outcome differences to determine, as well. At this point, it is most reasonable to continue to recommend the appropriate diet, weight gain, and exercise guidelines to all pregnant women, as outlined by the American College of Obstetrics and Gynecology."
The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research.