4 January 2000

Snoring and pregnancy - a potentially dangerous combination

by Kate Melville

Snoring is not restricted to men - fat, drunken, sleeping on their backs or otherwise. However for pregnant women it can also be a sign of hypertension and potentially be a risk factor for growth retardation of the fetus.

Hypertension and related medical problems are a leading cause of maternal death and an important cause of neonatal morbidity and mortality. However according to a new Swedish study of 500 women snoring is quite common during pregnancy. Other studies linked snoring with hypertension in middle-aged women, but according to Dr. Karl Franklin, of the Umea University Hospital in Sweden, no one investigated whether snoring is associated with hypertensive disorders of pregnancy. Snoring is a sign of elevated upper airway resistance and obstructive sleep apnea (OSA) and is associated with coronary artery disease (CAD) and arterial hypertension.

The researchers investigated snoring-related occurrences of pre-eclampsia, a toxemia of pregnancy distinguished by hypertension, edema (a buildup of fluids in body tissues), proteinuria (excessive serum proteins), as well as daytime sleepiness. The study included an analysis of Apgar scores that reflect an infants heart rate, respiratory effect, muscle tone, reflex irritability, and color, all measured shortly after birth. Results showed that snoring increased during pregnancy and by the third trimester, 24% of the women studies reported that they were either snoring or their level of snoring had increased (23% said their snoring had become habitual during the last week before delivery).

Sleep apnea was observed in 11% of habitual snorers and they also had more pronounced weight increase during pregnancy. Of the women who snored habitually 14% had pregnancy-induced hypertension compared to 6% of non-frequent snorers. In addition 10% who habitually snored met the definition of pre-eclampsia with hypertension and proteinuria compared with 4 percent of the nonfrequent snorers.

Daytime sleepiness increasingly grew among all women during pregnancy. Daytime sleepiness started earlier in pregnancy than did snoring. Edema of the face, hands, legs was reported as being greater among women who snored habitually 52% compared with 30 %for others).

Infants born to mothers who were habitual snorers tended to have lower birth weight and Apgar scores. 7% of mothers who were habitual snorers had babies with growth retardation compared with 2.6% among non-habitual snorers. Even after adjusting for weight, smoking habits and age, 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.

According to Dr. Franklin, "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 pre-eclampsia, are desirable and may answer the question of whether there is an etiologic link between increased upper airway resistance and pre-eclampsia."

So if your or your pregnant partner snores then it may be a good idea to see a respiratory specialist, or at least discuss this new research with your primary care physician - (we can already guess what they will tell you about pregnancy and smoking).