The University of Michigan researchers found that women who begin snoring during pregnancy are at strong risk for high blood pressure and preeclampsia.

The research, published in the American Journal of Obstetrics and Gynecology, showed pregnancy-onset snoring was strongly linked to gestational hypertension and preeclampsia, says lead author Louise O’Brien, Ph.D., associate professor in U-M’s Sleep Disorders Center.

“We found that frequent snoring was playing a role in high blood pressure problems, even after we had accounted for other known risk factors,” says O’Brien. “And we already know that high blood pressure in pregnancy, particularly preeclampsia, is associated with smaller babies, higher risks of pre-term birth or babies ending up in the ICU.”

The study is believed to be the largest of its kind, with more than 1,700 participants. It is the first study to demonstrate that pregnancy-onset snoring confers significant risk to maternal cardiovascular health.

Habitual snoring, the hallmark symptom of sleep-disordered breathing, was defined as snoring three to four nights a week. About 25 percent of women started snoring frequently during pregnancy and this doubled the risk for high blood pressure compared to non-snoring women.

O’Brien writes that these results suggest that up to 19 percent of hypertensive disorders during pregnancy might be mitigated through treatment of any underlying sleep-disordered breathing.

Pregnant women can be treated for sleep-disordered breathing using CPAP (continuous positive airway pressure). It involves a machine, worn during sleep, that uses mild air pressure to keep the airways open. It is possible that use of CPAP may decrease high blood pressure in pregnant women, and O’Brien has such a study currently underway to test this hypothesis.

“Hypertensive disorders of pregnancy are a leading global cause of maternal and infant deaths and cost billions of dollars annually to treat,” O’Brien says.

“By asking pregnant women about snoring, especially in those with high blood pressure already, obstetric healthcare providers could identify women at high risk for sleep-disordered breathing and intervene during the pregnancy. This could result in better outcomes for mother and baby.”

Additional authors: All from the University of Michigan: Ronald D. Chervin, M.D., M.S.; Alexandra S. Bullough, MBChB, FRCA; Jocelynn T. Owusu, M.P.H.; Kimberley A. Tremblay, M.S.; Cynthia A. Brincat, M.D., Ph.D.; Mark C. Chames, M.D.; and John D. Kalbfleisch, Ph.D.

The University of Michigan Sleep Disorders Center diagnoses and treats patients who have problems with their sleep or level of alertness. The Center is among the largest academic facilities of its kind in the country and includes several parts:  a number of general and more specialized Sleep Disorders Clinics; the Michael S. Aldrich Sleep Disorders Laboratory; the University of Michigan Sleep Disorders Laboratory – South State Street; active training programmes; and productive research projects.