1 Department of Perinatology and Gynecology, Poznan University of Medical Sciences, Poland2 Department of Respiratory Medicine, Alergology and Pulmonary Oncology, Poznan University of Medical Sciences, Poland3 Chair of Chemistry and Clinical Biochemistry, Department of Clinical Biochemistry and Laboratory Medicine, Poznan Univer-sity of Medical Sciences, Poland4 Department of Otolaryngology, Poznan University of Medical Sciences, Poland

Archives of Perinatal Medicine 19(4), 223-228, 2013 ORIGINAL PAPER

Obstructive sleep apnea in pregnancy

KAROLINA GRUCA-STRYJAK1, SZCZEPAN COFTA2, EWA WYSOCKA3,

JACEK BANASZEWSKI4, GRZEGORZ H. BRĘBOROWICZ1

Abstract

Objective: Pregnancy is associated with many physiologic changes along with changes in breathing during sleep,placing pregnant women at risk for the development of sleep-disordered breathing. The study aims were to assessthe prevalence of obstructive sleep apnea in pregnancy as well as their impact on the perinatological outcomes.Methods: We studied 101 pregnant women. They were enlisted in a prospective study divided into three parts:Part 1 – questionnaire on past and present sleep disorders including Epworth Sleepiness Scale. In Part 2 all preg-nant women underwent nocturnal polysomnography. In part 3-2 weeks after delivery, the patients were surveyedregarding fetal outcome and mode of delivery. Results: Obstructive sleep apnea (AHI > 5) was diagnosed in threepatients, which accounted for 3% of all studied women. All of them were in the third trimester of pregnancy. Thefirst patient course of pregnancy was uneventful. The other two patients were enrolled in the group of preg-nancies complicated by preeclampsia. Two patients due to severe obstructive sleep apnea (AHI > 30) were treatedby continuous positive airway pressure (CPAP). The use of CPAP led to normalization of respiratory parametersas well as to lowering blood pressure. Conclusion: Disorders of breathing during sleep contribute to the deve-lopment of various diseases or they degrade the overall phenomena. Therefore, it is essential to treat not onlythe primary disease, but also the accompanying sleep disorders.

Key words: pregnancy, sleep apnea, sleepiness, blood pressure

Inroduction

Sleep disturbances are common complaints duringpregnancy. Sleep disturbances are typically classified as:disturbed sleep quality, short/long sleep duration, re-stless leg syndrome and sleep disordered breathing(SDB). Physiologic and hormonal changes occurringduring pregnancy particularly concern progressive weightgain and pregnancy associated nasopharyngeal edema.These factors as well as the physical effect of the en-larging uterus decrease the functional reserve capacityand they increase the number of incidents of arousalsfrom sleep. All of these factors may increase the like-lihood of developing SDB or may magnify its effects.

Although snoring, the most common symptom of ob-structive sleep apnea (OSA), is common among pregnantwomen, the symptom is less specific for OSA than aresymptoms of gasping and choking or witnessed apneas.Apnea is defined as the restriction of the flow of airthrough the airways of at least 10 seconds accompaniedby declines in arterial oxygen saturation of at least 4%.Hypopnea is recognized when there is a reduction in theamplitude of the air passage of at least 50%, lastinglonger than 10 seconds. The exponent of the severity of

the above-identified episodes of breathing is apnea-hypopnea index [1]. Apnea and hypopnea often are com-bined with arousals, sleep fragmentation, reduced oxy-gen pressure and with an increase in the partial pres-sure of carbon dioxide, which is manifested by a decrea-se in arterial oxygen saturation. This, in turn, leads tostimulation of the sympathetic system, the activation ofwhich causes fluctuations in heart rate and in blood pres-sure [2- 4]. Following the recommendations of the Ame-rican Academy of Sleep Medicine in 1999 for diagnosisof OSA is to determine AHI > 5, combined with exces-sive daytime sleepiness, and at least two of the followingsymptoms: 1) habitual snoring, 2) choking or gaspingduring sleep, 3) arousals, 4) impaired concentration, fa-tigue during the day [1]. The value of AHI 5-30 episo-des/hour allows to identify moderate OSA, and with theAHI > 30 episodes/hour severe disease is recognized.

The prevalence of OSA in pregnancy has not beensystematically evaluated. It is estimated that approxima-tely 10-24% of pregnant women in the third trimester ofpregnancy suffer from sleep-related breathing disordersin the form of sleep apnea, and this proportion is signi-ficantly increased in women with preeclampsia and in

K. Gruca-Stryjak, S. Cofta, E. Wysocka, J. Banaszewski, G.H. Bręborowicz224

pregnancies complicated by intrauterine fetal growthrestriction (IUGR) [5-10]. The exact prevalence of OSAin pregnancy is unknown, and the sleep apnea remainsan unrecognized problem [10].

The study aims were to assess the prevalence ofobstructive sleep apnea in pregnancy as well as their im-pact on the perinatological outcomes.

Material and methods

1. Population

The study included 101 pregnant women.The first group consisted of 68 patients in the course

of normal pregnancies that were assigned to three sub-groups depending on the trimester of pregnancy.

The second group consisted of 33 patients in preg-nancies complicated by hypertension.

The women were recruited from outpatient clinicalpractice among colleagues of the research team andfrom Perinatology and Gynecology Department. All sub-jects provided their written informed consent for thestudy, which had the approval of the Local Ethics Advi-sory Committee.

2. Protocol

Part 1 of the study included: medical and obstetricchart review, completion of sleep disorders question-naire with the Epworth Sleepiness Scale, blood pressureassessment.

In Part 2 of our study we performed full overnightpolysomnography (PSG) on all 101 subjects, utilizinga recording system (Compumedics, Australia). We re-corded standard electrophysiologic signals includingelectroencephalography, electrooculography, electro-myography and electrocardiography. Furthermore, stan-dard respiratory signals including chest and abdominalmovements, nasal pressure flow heart rate and arterialoxyhemoglobin saturation (SaO2) were used. The sub-jects were all inpatients on the antenatal ward of Depart-ment of Perinatology, and were studied in a standardhospital bed.

In Part 3, two weeks following delivery, patientswere surveyed by telephone regarding fetal outcome andmode of delivery. Outcomes evaluated included newbornweight, gestational weeks at the time of delivery and1- and 5-min Apgar scores.

3. Statistical analysis

For statistical analysis, SigmaStat3.5 software wasused. The analysis of the results was based on the One

Way ANOWA for parametric, and Kruskall-Wallis ANOVAon Ranks for non-parametric distribution in the clas-sification of a single test with the test Turkey’a multiplecomparisons Holm-Sidak’a or Dunn’a. The value ofp < 0.05 was considered statistically significant.

ResultsObstructive sleep apnea (AHI > 5 with excessive

sleepiness ESS > 9) was detected in three patients,which accounted for 3% of all patients studied. Daytimesleepiness was assessed using the Epworth Scale (ESS).It concerned the assessment of the possibility of fallingasleep in eight defined situations. Moderate sleepiness(ESS 10-14) was observed in 1 patient. The other twohad severe degree of daytime sleepiness (values above14 points). All 3 patients were habitual snorers, whichmeans that they snore at least four nights per week. Thediagnosis of OSA was made in patients in the third tri-mester of pregnancy. The first patient with moderateOSA (AHI 5-30) had uneventful pregnancy. The othertwo patients with severe OSA (AHI > 30) were classifiedinto group of pregnancy complicated by preeclampsia(Fig. 1). Patient No. 2 was in twin pregnancy. The pa-tient No. 3 was extremely obese and additionally diag-nosed with diabetes. Clinical characteristics of this pa-tients with polysomnographic respiratory parameters arepresented in Table 1. In two patients due to severe ob-structive sleep apnea (AHI> 30) the treatment with thedevice producing continuous positive pressure withinthe airways (CPAP) was introduced. The patient withAHI value = 7.1, because of the absence of clinical sym-ptoms, did not require application of CPAP treatment.The effect of CPAP on blood pressure and selected poly-somnographic respiratory parameters are presented inTable 2.

Patient No. 1 gave birth at 40 weeks gestation bycaesarean section (indication: decelerations in cardioto-cography) of healthy male infant weighing 3360 g. Pa-tient No. 2 gave birth at 35 weeks gestation by caesa-rean section (indication: decelerations in cardiotocogra-phy of the first fetus) of two healthy babies with massesof 2000 and 2110 g. In both cases, the children received10 points the 1st and 5th minute in the assessment inApgar score. Patient No. 3 at 40 weeks of pregnancyunderwent physiological delivery. The newborn weighing1790 g was evaluated in the Apgar score at 6 and 9points respectively at 1st and 5th minutes of life. In allcases, the evaluation of the parameters of acid-basebalance from umbilical vessels was within the norm.

Obstructive sleep apnea in pregnancy 225

Fig. 1. Fragment of the polysomnographic study of pregnant women at 31st week in pregnancy complicated by preeclampsia and OSA showing the number of sleep apnea episodes

Table 1. Clinical characteristics pregnant women with OSAPatient No 1

Uncomplicatedpregnancy

Patient No 2Preeclampsia

Patient No 3Preeclampsia,

Gestational diabetes, ObesityAge 37 39 33Pregnancy-BMI (kg/m2) 28.4 27.5 64.1Neck circumference (cm) 39 43 44Mallampati score 3 4 4ESS – Epworth sleepiness scale 10 18 16Mean systolic blood pressure (mm Hg) 120 145 164Mean diastolic blood pressure (mm Hg) 80 102 105AHI – apnea-hypopnea index 7.1 82.1 77.5Mean SaO2 (%) 97 93 83The lowest SaO2 (%) 83 82 30

Table 2. Effects of treatment by means of CPAPPatient No 2 Patient No 3

before CPAP CPAP before CPAP CPAP

33 weeks ofpregancy

7 day treatmentof CPAP 34 weeks

of pregnancy

35 weeks ofpregnancy

11 day treatment of CPAP 37 weeks

of pregnancyESS – Epworth sleepiness scale 18 8 16 7AHI – apnea-hypopnea index 82.1 1.2 77.5 3.6Mean SaO2 (%) 93 97 83 94The lowest SaO2 (%) 82 94 30 83Mean systolic blood pressure (mm Hg) 145 134 164 151Mean diastolic blood pressure (mm Hg) 102 86 105 76

Discussion

Sleep apnea in pregnancy was first described byJoel-Cohen et al. in 1978 [11]. Most reports in the lite-rature concerns the descriptions of single cases [12-14].The limitations of the research concerns a small number

of patients in study groups. In addition, many studieswere based only on the questionnaire, and the resultsare not confirmed in polysomnographic study [7, 15-18].

Scientists have found that in pregnant women withhypertension habitual snoring and sleep apnea were

K. Gruca-Stryjak, S. Cofta, E. Wysocka, J. Banaszewski, G.H. Bręborowicz226

diagnosed more often [7, 15, 19, 20]. It is significant thatthe detected respiratory problems in women with pre-eclampsia are mild and in the general population couldbe considered as negligible. The episodes of apnea, hy-popnea or episodes of desaturation that could meet thecriteria for the diagnosis of obstructive sleep apnea areobserved very rarely in preeclamptic patients. However,these seemingly minor disturbance of air flow in upperairway contribute significantly to the increase in bloodpressure during sleep which is especially important inthe case of preeclampsia [21-23]. This means, that theincrease in blood pressure in these cases is not a conse-quence of the desaturation episodes and followed hy-poxia, but is associated with the vascular complicationsof SDB. Currently, the most popular hypothesis linkingpregnancy-induced hypertension with sleep disordersrelates to the partial obstruction within the upper airwayduring sleep. This, in turn, results in a relative increasein pCO2 concentration, which stimulates sympatheticsystem. In the case of preeclampsia damaged endothe-lium is “hypersensitive” on this stimulation and the res-ponse is exacerbated, leading to generalized vasospasm[21, 22, 24].

The effectiveness of the CPAP in patients with pre-eclampsia confirms the existence of the above presentedrelationship. In addition, it may result in the preventionof growth of pCO2, which is one of the best-knownvasoconstricting factors [23].

However, it must be emphasized that sleep disor-dered breathing in pregnant women may develop inde-pendently of the development of hypertension [22, 25,26]. This has been confirmed in our study. We found thatthe prevalence of obstructive sleep apnea in the groupof physiological pregnancies was 1.5% and it was a mildform of OSA (AHI< 30). While in the group of pregnan-cies complicated by hypertension the incidence of OSAwas 6% and it were severe obstructive sleep syndromeswith the values of the AHI above 70. These problemsalso contributed to the increase in blood pressure duringthe course of preeclampsia.

Breathing disorders during sleep also have an ad-verse effect on the health of pregnant women and theireffects can be distant. They not only caused deteriora-tion in the quality of life, but most of all they influenceson life duration. Mortality in the course of obstructivesleep apnea refers to sudden death during sleep, to thedevelopment of chronic diseases, especially cardiovas-cular and to traffic accidents and accidents at work,which are caused by excessive daytime sleepiness. Inthe literature we can find several case reports of deaths

during sleep that occurred during polysomnographyexamination. The first case involved a 52-year-old obesewomen (BMI 67.3 kg/m2). After the subsequent obstruc-tive sleep apnea there has been no return of sponta-neous ventilation, resulting in cardiac arrest. An autopsyshowed no other cause of death [27]. The second casealso concerned the obese (BMI 60.2 kg/m2) woman aged60 years with heart failure and severe OSA [28]. Stop-ping of breathing is one of the mechanisms of suddendeath in sleep. the others concerns acute cardiovascularevents and cardiac arrhythmias. Particularly serious arethe ventricular arrhythmias. High heart rate variabilitydue to firstly vagus nerve stimulation (apnea-bradycar-dia) and secondly parasympathetic activation (back-venti-lation tachycardia) predispose to them. Imposition ofacute hemodynamic effects on chronic, present in OSA,risk factors may be another mechanism of sudden car-diac arrest in this population. Severe bradycardia or ta-chycardia may reduce cardiac output and reduce perfu-sion of the central nervous system. Researchers havefound that during obstructive sleep apnea is a significantdecrease in cerebral blood flow. Moreover, it has beendemonstrated that cerebrovascular sensitivity to hyper-capnia is reduced in this group of patient [29, 30]. Thissuggests that OSA may be an important risk factor forcerebrovascular events.

Obstructive sleep apnea causes a number of meta-bolic and endocrine system implications. Scientific stu-dies clearly indicate that OSA is an integral componentof the metabolic syndrome, as well as visceral obesity,hypertension and impaired glucose and lipid metabolism[31, 32]. Has also been shown, that the incidence ofsnoring and sleep apnea contributes to the developmentof diabetes, increased platelet aggregation and reduceplasma fibrinolytic activity [33, 34].

A retrospective study conducted by He et al. relatedto 5-year follow-up of deaths among patients with OSA[35]. The study demonstrated that AHI has a high pre-dictive value in the assessment of mortality in patientswith untreated obstructive sleep apnea. The value of AHI> 20 increased mortality of 37% in 8 years observation.

All the above presented information are very impor-tant, particularly with regard to the two described pa-tients with severe obstructive sleep apnea. Despite theiryoung age, both patients are at high risk for cardiovas-cular complications. In the second case, due to extremeobesity with co-morbidities problems (pregnancy indu-ced hypertension, gestational diabetes) we made diagno-sis of metabolic syndrome. In both patients, due to con-comitant with preeclampsia disordered breathing during

Obstructive sleep apnea in pregnancy 227

sleep can cause excessive release of endothelin, catecho-lamines, and vascular endothelial growth factor – VEGFthat the mitogenic effect can lead to preservation of hy-pertension [36]. Therefore, it is very important to furtherdiagnosis and treatment of these patients in order toprevent occurrence of cardiovascular complications, be-cause they are exposed to them to a very large extend.

Basing on the guidelines of treatment for obstructi-ve sleep apnea in the general population Pien andSchwab created recommendations for pregnant women[37]. Treatment of choice for symptomatic pregnant wo-men diagnosed with moderate OSA (AHI 5-30 episo-des/hour) or with episodes of desaturation below 90%and in pregnant women with severe OSA (AHI > 30 epi-sodes/hour) is breathing at a constant positive pressureairway – CPAP. Blyton and colleagues in their studyfound that the use of CPAP in pregnancy complicated bypreeclampsia caused an increase in cardiac output dueto a reduction in peripheral resistance [38]. A study con-ducted by Guilleminault et al. in 2004, including 12 wo-men, who have included treatment with CPAP, alsoconfirmed these findings and pointed to the fact that thismethod is safe and well tolerated by patients [39]. Re-ports related to the use of CPAP during pregnancy arenot numerous, but none of the work has shown its harm-ful effects on the fetus [12, 14, 40, 41].

Guilleminault et al. in 2007 conducted a prospectivestudy of early application of CPAP and their impact onperinatological outcomes. Treatment with CPAP was ap-plied in 12 pregnant women in the first trimester ofpregnancy with risk factors for the development of pre-eclampsia. This made it possible to alleviate breathingproblems during sleep, but it was insufficient to avoidadverse results in the mother and the fetus [42]. How-ever, in a randomized study conducted by Poyares'a andcolleagues, they compared treatment with CPAP to stan-dard medical treatment [43]. It was noted that the com-bination of these two forms of therapy during early preg-nancy improved blood pressure control, without theneed to increase antihypertensive treatment. However,the results on the state of the newborn were similar inboth groups. Skilton, et al. observed a reduction in thenumber of fetal movements in women with preeclampsiacompared to the control group (319 vs. 689, p < 0.0001),and this number was significantly increased after intro-ducing CPAP treatment (p < 0.0001) [44].

In our study, after diagnosis of severe obstructivesleep apnea in two patients, the CPAP therapy was intro-duced. The use of this type of treatment allowed, as wellas normalization of respiratory parameters in polysom-

nography, to lower blood pressure without changes intheir drug therapy. We are aware that our study haveseveral limitation. The sample size of OSA was verysmall. The need exists for additional studies to explainthe effects of OSA and treatment by means of CPAP onmaternal-fetal outcome.

Conclusion

OSA adversely affects the health of the mother andthe fetus. It has been proved that there are many rela-tionships between sleep and health. Sleep disorders anddisorders of breathing during sleep contribute to the de-velopment of various diseases or they degrade the overallphenomena. Therefore, it is essential to treat not onlythe primary disease, but also the accompanying sleep dis-orders.

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AcknowledgmentThis work was performed at the Department of Perinatologyand Gynecology, Poznan University of Medical Sciences andreceived financial support from the National Science Centre,Poland grant 2131/B/P01/2009/37 (NN 407213137).

The authors disclose any personal or financial support or anyinvolvement with organizations having financial interest in thesubject matter. The authors are unaware of any conflict ofinterest.

J Karolina Gruca-StryjakDepartment of Perinatology and GynecologyPoznan University of Medical Sciences60-535 Poznań, ul. Polna 33, Polande-mail: karolagruca@poczta.onet.pl