snoring during pregnancy, Snoring, association with fetal outcome, Frequent snoring, medical records, pregnancy, preeclampsia

articles about snoring during pregnancy

Self-reported snoring in pregnancy: association with fetal outcome

April, 1996 by Daniel I. Loube, J. Steven Poceta, Manuel C. Morales, Mark D. Peacock, Merrill M. Mitler

Objectives: To determine the incidence of self-reported snoring in pregnant compared with nonpregnant women. To compare indicators of fetal outcome in pregnant women with self-reported frequent snoring vs those without snoring.

Study design: Prospective, nonrandomized screening and comparison between groups.

Patients: Three hundred fifty pregnant women and 110 age-matched nonpregnant women.

Methods: Survey evaluating self-reported snoring. For the pregnant women, infant birthweight, APGAR scores, and other indicators of fetal outcome were obtained by record review.

Results: Frequent snoring was reported in 14% of the pregnant women vs 4% of the nonpregnant women [([chi].sup.2]=6.2; df=1; p[less than]0.05). The pregnant women who reported frequent snoring did not have deliveries resulting in infants with evidence of an increase in compromised outcomes.

Conclusions: Frequent snoring is reported more often in pregnant than in nonpregnant women. Snoring mothers do not appear to be at increased risk for delivering infants with fetal compromise as might be expected with the concomitant occurrence of obstructive sleep apnea.

Snoring in pregnancy has not been well studied, although it has been acknowledged in the otolaryngologic literature as occurring in association with rhinitis of pregnancy which is common in the third trimester.(1) Preliminary data from a study by Schutte et al(2) suggests self-reported snoring occurs in 27% of pregnant women in the third trimester. The frequent occurrence of self-reported snoring during pregnancy is further supported by a study of Redline et al(3) that shows that women underreport symptoms of disturbed breathing during sleep, including snoring.

Self-reported snoring is associated with an increase in the occurrence of obstructive sleep apnea (OSA) in middle-aged men.(4) This association is important because of the pathophysiologic consequences of untreated OSA which include systemic hypertension,(5) myocardial infarction,(6) pulmonary hypertension,(7) and neuropsychiatric sequelae.(8) It is controversial whether snoring without the occurrence of OSA leads to any of these pathophysiologic consequences.(9) Guilleminault et al(10) describe the upper airway resistance syndrome (UARS) as typically occurring in snorers without classic OSA, yet still resulting in sleep fragmentation and excessive daytime sleepiness. Whether untreated UARS results in cardiopulmonary abnormalities is unclear.

Despite older studies that suggest OSA is infrequent in women, Young et al(4) found the incidence of OSA as defined by a respiratory disturbance index (RDI) greater than five events per hour to be 19% for women age 30 to 60 years old with self-reported habitual snoring. The occurrence of OSA was less frequent in younger women, but might be expected to be higher in pregnant women because of the association with increased snoring. Yet to our knowledge, only four case reports of documented OSA in pregnant women have been published.(11),(12),(13),(14) Of concern is that two of these case reports included pregnancies that resulted in infants with intrauterine growth retardation (IUGR).(12),(13) Since chronic maternal hypoxemia is associated with IUGR in a number of diseases, and OSA is typically characterized by recurrent episodes of oxyhemoglobin desaturation, some investigators believe OSA may lead to IUGR.(15)

Because the association between pregnancy and snoring is not well established, we sought to prospectively determine if self-reported snoring is increased with pregnancy. We also sought to determine if the epidemiologic and pathophysiologic associations between self-reported frequent snoring and OSA evident in other populations were important in pregnant women, especially with respect to impact on fetal outcome.

Table 1--Demographics and Self-reported Symptoms for Pregnant andNonpregnant Women(1)

Following delivery, research assistants who were unaware of whether the patients reported snoring or apnea reviewed medical records for infant birth weights, APGAR scores, and documentation of any infant physical abnormalities. IUGR was defined by a fetal birth weight below the tenth percentile for gestational age.

Statistical analysis was performed with a computer program (SPSS/PC+V2.0; SPSS Inc; Chicago), on pooled data for patient groups. Interval type variables were evaluated using two-tailed t tests with results confirmed with Mann-Whitney Rank Sum tests for values that were significantly different. [[chi].sup.2] tests were used to compare the observed frequency of events between groups. Tests and comparisons between groups were considered statistically significant for p values less than 0.05.

RESULTS

Ninety-five percent of nonpregnant women and 91% of pregnant women offered the questionnaires agreed to participate in the study. One hundred ten nonpregnant women and 350 pregnant women completed screening questionnaires with results presented in Table 1. There were no significant age or height differences between these groups, but pregnant women weighed significantly more than nonpregnant women. As a group, the pregnant women had a body mass index (BMI)(weight/height(2)) of 28.2 [kg/m.sup.2] at the time of initial screening, which was at a mean of 30 weeks of estimated fetal gestation. This BMI was higher than that recommended for a normative population of pregnant women at this time during pregnancy.(21)

It is reassuring that self-reported frequent snorers did not deliver infants with a higher prevaleance of IUGR or other manifestations of chronic hypoxemia. However, this finding is not unexpected when two factors are taken into account. First, Hoffstein(33) showed that nonapneic snorers are unlikely to have nocturnal oxygen saturation. Second, even if transient nocturnal desaturation occurs during pregnancy, it is unlikely to adversely affect the fetus because adequate oxygen delivery is facilitated by the high oxygen carrying capacity of fetal hemoglobin, the high hemoglobin concentration of fetal blood, and the enhanced uptake and delivery of oxygen in the relatively acidemic fetal circulation.(34)

In conclusion, our study shows that self-reported frequent snoring is more prevalent in pregnant women than in nonpregnant women. We also found that self-reported frequent snoring with pregnancy is not associated with increased daytime sleepiness or compromised fetal outcome as might be expected with an association with more severe forms of OSA. Comprehensive studies involving NPSG on larger numbers of pregnant women will be helpful in further characterizing this remarkable physiologic state.

REFERENCES

(1) Gluckman JL, Stegmoyer R. Rhinitis. In: Paparella M, ed. Disorders of the head and neck. Philadelphia: WB Saunders, 1992; 1892-93

(2) Schutte S, Del Conte A, Doghramji K, et al. Snoring during pregnancy and its impact on fetal outcome [abstract]. Sleep Res 1995; 24:199

(3) Redline S, Kump K, Tishler PV, et al. Gender differences in sleep disordered breathing in a community-based sample. Am J Respir Crit Care Med 1994; 149:722-26

(4) Young T, Palta M, Dempsey J, et al. The occurrence of sleep disordered breathing among middle-aged adults. N Engl J Med 1993; 328:1230-35

(5) Hillman DR. Sleep apnea and myocardial infarction. Sleep 1993; 16:S23-24

(6) Hla KM, Young TB, Bidwell T, et al. Sleep apnea and hypertension. Ann Intern Med 1994; 120:382-88

(7) Bradley TD, Rutherford R, Lue F, et al. Role of daytime hypoxemia in the pathogenesis of right heart failure in the obstructive sleep apnea syndrome. Am Rev Respir Dis 1985; 131:835-39

(8) Engelman HM, Douglas NJ. Cognitive effects and daytime sleepiness. Sleep 1993; 16:S79-84

(9) Hoffstein V. Blood pressure, snoring, obesity, and nocturnal hypoxaemia. Lancet 1994; 344:643-45

(10) Guilleminault C, Stoohs R, Young-do K, et al. Upper airway sleep-disordered breathing in women. Ann Intern Med 1995; 122:493-501

(11) Sherer DM, Caverly CB, Abramowicz JS. Severe obstructive sleep apnea and associated snoring documented during external tocography. Am J Obstet Gynecol 1991; 165:1300-01

(12) Schoenfield A, Ovidia Y, Neri A, et al. Obstructive sleep apnea--implications in maternal-fetal medicine. Med Hypotheses 1989; 30:51-4

(13) Charbonneau M, Falcone T, Cosio MG, et al. Obstructive sleep apnea during pregnancy: therapy and implications for fetal health. Am Rev Respir Dis 1991; 144:461-63

(14) Hastie SJ, Prowse K, Perks WH, et al. Obstructive sleep apnoea during pregnancy requiring tracheostomy. Aust NZ J Obstet Gynaecol 1989; 29:365-67

(15) Kryger MH. Restrictive lung diseases. In: Kryger MH, Roth T, Dement WC, eds. Principles and practices of sleep medicine. Philadelphia: WB Saunders, 1994; 769-75

(16) Johns MW. A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale. Sleep 1991; 14:540-45

(17) Kapuniai LE, Andrew DJ, Crowell DH, et al. Identifying sleep apnea from self-reports. Sleep 1988; 11:430-36...

For more info about snoring during pregnancy, please visit CHEST.

Snoring in pregnancy: disease or not?

April, 1996 by Michael R. Littner

In this issue of CHEST, the report of Loube and colleagues (see page 885) is the first large-scale prospective questionnaire study on snoring in pregnant, compared with nonpregnant, women (average age 25 years). This study suggests that prevalence of snoring and apnea is not increased, that frequent snoring is more common, and that there is no obvious effect on fetal outcome. It also confirms that severe obstructive sleep apnea (OSA) is rare in pregnant women.(1),(2)

Several of the authors' conclusions deserve comment. First, the conclusion that frequent snoring is more common needs to be confirmed. The use of self-reported snoring among women who probably have a roommate, compared with nonpregnant women (the controls) who may not, would almost certainly bias the study.(3) Moreover, frequent snoring does not generally correlate with greater degrees of apnea in the current study or most other studies.(3)(4)(5)(6)(7) Some studies report a correlation but mainly with the "always" rather than "often" snoring group.(8)(9)(10) Additionally, loud snoring is generally a better indicator of apnea.(3),(4) Of note, women may actually underreport snoring(11) and other symptoms of OSA.(12)

Second, the authors' hypothesis on fetal outcome derives from the observation that maternal hypoxemia can produce intrauterine growth retardation (IUGR) (ie, below the 10th percentile for gestational age).(13),(14) Additionally, 9 of 16 reported (although not necessarily fully documented) cases of apparently severe OSA had IUGR.(15)(16)(17)(18)(19)(20)(21) However, not one of 350 pregnant women in this study was documented to have apneas greater than 20/h, a level which may be considered moderate, and only one was documented with desaturations less than 90%, a level which potentially may endanger the fetus.(14) If IUGR occurs in 50% of cases more severe than observed in the present study, then it would probably take thousands of pregnancies to find sufficient cases of IUGR for analysis.

What can we learn from this study? First, snoring alone is not a disease in pregnant women in this age group. Perhaps as suggested by the authors, the negative features of pregnancy such as edema of the pharynx and increase in body weight are counterbalanced by an increase in progesterone and other undefined factors of pregnancy.

Third, snoring alone is not a good marker of OSA in pregnant women as has been previously noted in other populations. Based on several other studies(3)(4)(5)(6)(7),(9) and the authors' approach to identifying apneic patients, observed frequent apnea would appear to be a much better marker. For example, one woman reporting apnea did not report frequent snoring in the authors' study. Addition of snoring intensity may also help.(3),(4),(11)

Fourth, based on this study and others, pursuing a diagnosis of sleep apnea in snoring pregnant women would not appear to be warranted unless there is loud snoring and frequent (often or usual) apnea. Sleepiness would appear to be less discriminatory since hypoxemia is the important fetal variable and since these women were already mildly sleepy with an Epworth Sleepiness Scale (ESS) of about 9.(22)

Once a pregnant woman is suspected to have OSA, overnight pulse oximetry or full polysomnography are diagnostic options. We believe that since hypoxemia is the important insult to the fetus, overnight oximetry would be the most definitive approach to defining a fetus at risk. Full polysomnography would be reserved for maternal evaluation if clinically indicated. Other assessments of fetal well-being such as fetal heart rate monitoring (nonstress testing or contraction stress testing), serial sonorgraphic measurements for appropriate growth, fetal kick counts, or umbilical Doppler flow studies might define if the risk is potential or realized.(14)

Should OSA with hypoxemia be established then discretion would dictate vigorous treatment of the hypoxemia, whatever the usual approach might be for the mother. This could include nasal-continuous positive airway pressure or variants, a dental prosthesis, tracheostomy, or other surgery if not a risk to the fetus. Should these approaches not be acceptable or not tolerated by the woman, or should the response be insufficient, overnight supplemental oxygen therapy should be considered.(23) Should prevention of fetal hypoxemia be unsuccessful, prompt delivery may be necessary if indicated by the usual criteria for fetal assessment.(14) Fortunately, IUGR caused by hypoxemia is generally associated with a favorable outcome if followed closely with fetal surveillance.(14)

Future directions for this research are not clear. Because of the large numbers of pregnant women that would be needed, a prospective study would not appear to be feasible. Examination of mothers of documented cases of IUGR for the presence of OSA is an alternative approach. A speculative direction would be to look at other abnormal births of unexplained etiology such as cerebral palsy for the possibility of OSA as a cause. In any case, the good news is that pregnancy in young women rarely appears to be a risk factor for moderate to severe OSA...

For more info about snoring during pregnancy, please visit CHEST.

Snoring during pregnancy linked to reduced fetal growth

NEW YORK, Jan 17 (Reuters Health) -- Pregnant women who snore are more likely than non-snorers to have pregnancy-related high blood pressure and are at increased risk of having an infant who is considered small for gestational age, researchers report.

Overweight women may be at particularly high risk, according to Dr. Karl A. Franklin of University Hospital in Umea, Sweden, and colleagues. "Women who reported habitual snoring were heavier before pregnancy and gained more weight during pregnancy," they report in the January issue of the journal Chest.

Snoring is a common problem in pregnancy. The study of 502 women who had just given birth found that 23% snored during pregnancy while just 4% snored before they became pregnant.

Fourteen percent of women who snored had high blood pressure compared with only 6% of non-snorers, while preeclampsia developed in 10% of snorers compared with 4% of non-snorers, the researchers note. Preeclampsia is a dangerous condition characterized by elevated blood pressure, swelling in the hands, feet and face, and the presence of protein in the urine.

Examining the weight-for-gestational-age of babies born to women in the study, the authors report that fetal growth was slowed in 7.1% of infants born to snoring women compared with 2.6% born to non-snoring women.

Overall, habitual snoring during pregnancy was associated with double the risk for high blood pressure, and nearly 3.5 times the risk for slowed fetal growth, compared with non-snorers.

It is not clear if pregnancy-related high blood pressure leads to snoring by causing fluid build-up in the throat that narrows the airway or if snoring itself can actually lead to complications.

The investigators point out that snoring can be an sign of sleep apnea -- an intermittent blockage of the upper airway that can cause individuals to stop breathing for a few seconds at a time dozens or even hundreds of times per night. Sleep apnea has been linked to a rise in blood pressure in both men and women, and in the study, occurred in 11% of snorers compared with just 2% of non-snorers.

The finding suggests that "upper airway resistance during sleep may affect the fetus and supports the previously suggested relationship between sleep apnea and intrauterine growth retardation," Franklin and colleagues write.

More info about snoring during pregnancy, please visit Personal MD.