Snoring In Pregnant Women Associated With Hypertension And Fetal Growth Retardation

Hypertension disorders during pregnancy are a leading cause of maternal death in the United States and Great Britain and are important causes of neonatal morbidity and mortality. The cause of these disorders are still unknown.

Snoring is quite common in pregnancy, and investigators in Sweden studied more than 500 pregnant women to see what effect snoring had on their health. Earlier studies have linked snoring with hypertension in middle-aged women, but according to Karl Franklin, MD, FCCP, and colleagues at the Umea University Hospital in Sweden, no one has investigated whether snoring is associated with hypertensive disorders of pregnancy. Snoring is a sign of increased upper airway resistance and obstructive sleep apnea (OSA) and is known to be associated with arterial hypertension and coronary artery disease (CAD).

Investigators looked into the snoring-related occurrence of preeclampsia, a toxemia of pregnancy characterized by hypertension, proteinuria (excessive serum proteins), and edema (a buildup of fluids in body tissues), as well as daytime sleepiness, and infant outcome. The study included a questionnaire that women filled out on the day of their delivery with the involvement of their husband or partner. It also included analyzing Apgar scores which reflect the infants heart rate, respiratory effect, muscle tone, reflex irritability, and color, all measured shortly after birth. Snoring increased during pregnancy. By the third trimester, 24 percent of the women reported that they had begun snoring or increased their level of snoring.

Twenty-three percent said their snoring had become habitual during the last week before delivery. Habitual snoring was described as snoring every night or almost every night. Sleep apnea was observed in 11 percent of habitual snorers compared with 2 percent of the nonfrequent snorers. The habitual snorers also had a more pronounced weight increase during pregnancy. Fourteen percent of the women who snored habitually had pregnancy-induced hypertension as compared with 6 percent of the nonfrequent snorers. Ten percent of the women who habitually snored met the definition of preeclampsia with hypertension and proteinuria compared with 4 percent of the nonfrequent snorers. Daytime sleepiness increasingly grew among all women during pregnancy, and no marked differences were observed between the habitual snorers and the nonfrequent snorers. Daytime sleepiness started earlier in pregnancy than did snoring. Edema was reported as being greater among women who snored habitually. Edema of the face, hands, legs, or feet occurred in 52 percent of the habitual snorers compared with 30 percent for others.

Infants born to mothers who were habitual snorers more frequently had lower birth weight and lower Apgar scores, a finding researchers described as "novel." More than seven percent of mothers who were habitual snorers delivered an infant with growth retardation at birth compared with 2.6 percent among nonhabitual snorers. After adjusting for weight, age, and smoking habits, snoring remained as a significant predictor of growth retardation. In addition to snoring, smoking was also found to be an independent predictor of growth retardation. An Apgar score of less than seven was more common in infants born to habitual snorers as compared with infants born to occasional or nonsnorers. For example, 12.4 percent of infants of habitual snorers who were given an Apgar test at one minute after delivery had scores of less than seven compared with 3.6 percent of the infants of nonfrequent snorers who were given the Apgar test one minute after delivery. Statistically, the percentage differences were even greater when the test was administered five minutes after delivery, but less frequent for both habitual snorers and infrequent snorers.

Dr. Franklin noted that all of the subjects who snored habitually and had preeclampsia started to snore before any sigh of hypertension or proteinuria was present and that habitual snoring was related to sleep apneas. "This," he said, "indicates that nocturnal upper airway obstruction may contribute to the development of pregnancy-induced hypertension and preeclampsia. It is possible," he added, "that pregnant women are especially vulnerable to increases in upper airway resistance, as breathing may also be restricted by an increase in the abdominal pressure affecting the diaphragm. Respiratory sleep studies, including the treatment of sleep apnea in women with preeclampsia, are desirable and may answer the question of whether there is an etiologic link between increased upper airway resistance and preeclampsia."

CHEST is published by the American College of Chest Physicians which represents 15,000 members who provide clinical, respiratory, and cardiothoracic patient care in the U.S. and throughout the world.