Women who frequently snore-at least three nights a week-run a substantially higher risk of developing gestational diabetes during pregnancy than non-snorers.

That is the conclusion of a Northwestern University research study that tracked 189 women during their pregnancies. The women completed a sleep survey when they were between six and 20 weeks pregnant and then again during their third trimester. The researchers found that snorers had a 14.3 percent chance of developing gestational diabetes, versus 3.3 percent among non-snorers.

The study, which is the first to link snoring to gestational diabetes, took into account other factors that can contribute to the disease, including age, ethnicity, and body mass index.

The study also found that during pregnancy, women who were previously non-snorers may begin snoring. Early in the study, 11 percent of the women being tracked reported frequent snoring. However, by the third trimester, 16.5 percent reported snoring frequently-a 50 percent increase in snorers.

Why there's a link between snoring and gestational diabetes is not clear, says the study's author, Dr. Francesca Facco. She theorizes that the increased weight and fluid retention brought on by pregnancy blocks airflow through the mouth and nose. Poor air flow and diminished oxygen intake can cause what she calls "a cascade of events" in a woman's body, leading to heightened blood pressure, inflammation, and metabolic changes that can lead to diabetes.

Gestational diabetes, in which blood sugar levels become very high in women who have not previously been diagnosed with the disease, occurs in about 4 percent of pregnant women.

Post partum, the vast majority of women with gestational diabetes become completely symptom-free-about 90 percent. Another eight percent retain impaired glucose tolerance, which can be a precursor to type 2 diabetes, while 2 percent come away from their pregnancy with full-blown type 2.

Now that she has established an association between snoring and gestational diabetes, Facco says, healthcare providers should look into sleep therapies as a means of blocking the disease's development. Simply helping the airway stay open while sleeping during pregnancy could be enough to avert the problem.