Snoring during pregnancy is surprisingly common, although the physiological reason explaining why a woman would start snoring during pregnancy is unclear. The most commonly held theory is that the sleep disordered breathing is as a result of the weight gain which often accompanies pregnancy.
Regardless of the reason, the problem is that snoring during pregnancy may be a sign of sleep disordered breathing conditions which put women at risk for high blood pressure. According to a new study, this is a potentially serious complication for the mother and baby.
The study, done at the University of Michigan's Sleep Disorders Center, monitored more than 1,700 pregnant women who were at least 28 weeks pregnant. Among those whose snoring began during pregnancy, about 10 percent had pregnancy-related hypertension, compared with 4.5 percent of those who did not snore.
In addition, 13 percent of those whose snoring began during pregnancy had preeclampsia, compared with 8 percent of those who did not snore. High blood pressure in pregnancy is linked with an increased risk of premature birth and smaller babies.
Any pause or obstruction in breathing during sleep increases the activity of the nervous system, which in turn increases blood pressure, said Professor Julie O'Brien, the research leader.
The findings held even after the researchers took into account factors that could affect blood pressure, such as the mother's age, race, smoking habits and weight gain in pregnancy.
The researchers estimate that close to 19 percent of pregnancy-related high blood pressure cases, and 11 percent of preeclampsia cases, could be helped by treating any sleep disordered breathing.
A separate study published earlier this month found that babies born to women with sleep apnea were at increased risk for admission to the neonatal intensive care unit.
"If sleep apnea really is playing a role in these outcomes, then this is a clear opportunity that we can intervene and hopefully improve some of those pregnancy outcomes," O'Brien said.
Pregnancy, in fact any weight gain, is known to put people at risk for breathing problems during sleep, including snoring, the researchers said. Earlier studies have also linked breathing problems in sleep to an increased risk of high blood pressure in the general population.
O'Brien and colleagues are now conducting a study to see if treating breathing problems with continuous positive airway pressure (CPAP) reduces high blood pressure in pregnant women.
The new study was published online in the American Journal of Obstetrics and Gynecology.