Snoring in pregnant women is often a sign of induced hypertension and may be a contributing factor in infants with low birth weight, a study conducted by researchers at Sweden's Umea University Hospital has determined (Chest 2000;117:137-41).
"It is possible that pregnant women are especially vulnerable to increases in upper airway resistance, as breathing may also be restricted by an increase in abdominal pressure affecting the diaphragm," says lead investigator Dr. Karl Franklin, a member of the Department of Respiratory Medicine at Umea University Hospital. FIGURE
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More than 500 women took part in the study, which included a questionnaire filled out on the day of delivery, as well as analysis of Apgar scores.
The researchers found that snoring increased significantly during pregnancy. Twenty-three per cent of the women reported that their snoring had become habitual during the week before delivery. Fourteen per cent of the women who snored habitually had pregnancy-induced hypertension, compared with only 6% of the nonfrequent snorers. In addition, sleep apnea was found in 11% of the women who snored habitually. Among the less frequent snorers, this condition was observed in just 2% of the women. Ten percent of the frequent snorers met the medical criteria for pre-eclampsia. Only 4% of the less frequent snorers met the criteria. In particular, edema was found to be much more prevalent among snorers than nonsnorers. Fifty-two per cent of the women who snored habitually had edema of the legs, feet, hands or face, compared with 30% of the study's other participants.
"We [also] found that snoring was related to babies who were born small for their gestational age," said Franklin. "Snoring was a risk factor of the same magnitude as smoking and independent of smoking, weight and age of the mother."
More than 7% of the mothers who snored habitually gave birth to an infant with lower-than-average birth weight, compared with 2.6% of other mothers in the study group.
"I believe that snoring is a cause of intrauterine growth retardation," said Franklin. "However, it is harder for me to believe that snoring causes hypertension. Perhaps it worsens an already existing hypertensive disease. Further studies are needed to see whether the relationship is causal or not."