BOSTON (FRONTLINE MEDICAL NEWS) – Women who were prepregnancy, frequent, and loud snorers during pregnancy had a significantly higher risk of preterm or early term delivery, in a study presented at the annual meeting of the Associated Professional Sleep Societies.

“The fact that there is an association between snoring and time to delivery in a cohort which is not hypertensive is alarming, and I think that treatment for snoring earlier on in pregnancy may alleviate some of these outcomes,” reported Galit Levi Dunietz, PhD, MPH, of the University of Michigan in a session at the meeting.

Indeed, despite this otherwise being a low-risk cohort, about 25% of the women who fell into the chronic, loud snoring category had preterm or early term delivery as defined by the American Congress of Obstetricians and Gynecologists’ guidelines. According to these guidelines, early term delivery is 37 to 38 weeks gestation and preterm delivery is before 37 weeks.

Compared with nonsnorers, frequently loud snorers had about a 60% increased risk of preterm delivery even after adjusting for baseline body mass index, smoking, education, race, and parity. Pregnancy-onset snoring and infrequent or quiet snoring were not associated with preterm birth.

A limitation on the findings was that only a small number of women (4% of the sample) fell into the chronic, frequent, and loud snoring category. These women, however, had significantly lower mean gestational age, mean baseline BMI, and were more likely to be smokers, as compared with nonsnorers and quiet frequent or infrequent snorers.

“I think this is excellent work because it’s a big question,” said Dr. Omavi Gbodossou Bailey, MD, MPH from the University of Arizona, Pheonix, in a Q&A session at the conference. “As a primary care physician, I deliver babies and I also deal with sleep and when I ask the ob.gyns. about sleep apnea in this patient population, they’re not usually interested.”

Dr. Bailey noted in an interview that, often, women who had uncomplicated first pregnancies return with later pregnancies heavier, more sleep deprived, and snoring. “Then, they have higher risk for complications in the second or third pregnancy,” he said.

Snoring is common in pregnancy, affecting about 35% of women, and pregnancy itself is a risk factor for snoring. Previous studies have associated snoring with key pregnancy morbidities including hypertension, preeclampsia, and gestational diabetes, but, prior to this research, the few studies that had looked at snoring and preterm delivery had shown inconsistent results.

The researchers recruited 904 pregnant women in their third trimester and without hypertension or diabetes from prenatal clinics at the University of Michigan cared for between 2008 and 2011. The women were queried on the frequency of their snoring (from never to three or more times per week) along with its intensity (from nonsnoring to loud or very loud snoring). They were also categorized, based on self-report, as either chronic/prepregnancy snorers or incident/pregnancy-onset snorers.

In this low-risk cohort, 25% of the women reported incident snoring and 9% reported chronic prepregnancy snoring.

“The combination of snoring frequency and intensity may be a clinically useful marker to identify otherwise low-risk women who are likely to deliver earlier,” said Dr. Dunietz.

This study was funded by the Gilmore Fund for Sleep Research, the University of Michigan Institute for Clinical and Health Research, and the National Heart, Lung, and Blood Institute. Dr. Dunietz reported having no financial disclosures.