SAS and Pregnancy


1.    Snoring, Pregnancy-Induced-Hypertension–and Growth Retardation     of the Fetus (CHEST-2000-137.pdf)

 Snoring may be regarded as a common feature of pregnancy, as 23% of the women in this study snored habitually and 25% snored occasionally, whereas only 4% had snored habitually prior to pregnancy.

Habitual snoring during pregnancy was related to hypertension, preeclampsia, edema, and increased body weight of  the mother and was also associated with growth retardation of the fetus and a low Apgar score for the infant. Habitual snoring was independently predictive of hypertension and growth retardation, even when weight, age, and smoking were controlled for.

All of the women who snored habitually and had preeclampsia started to snore before any sign of hypertension or proteinuria was present, and habitual snoring was related to witnessed sleep apneas. This indicates that nocturnal upper airway obstruction may contribute to the development of pregnancy-induced hypertension and preeclampsia. 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 the abdominal pressure affecting the diaphragm.

Characteristics Habitual Snorers Nonfrequent Snorers
Hypertension 14% 6%
Preeclampsia 10% 4%
Small for gestational age 7.1% 2.6%
Apgar score ≤ 7 after 1 min  Apgar score ≤ 7 after 5 min 12.4%




2.  Sleep and its Disorders in Pregnancy (SharmaSA.pdf)

 By their third trimester of pregnancy 97% of women report sleep disturbance. Sleep can be affected during pregnancy due to several reasons:

  • Hormones: Estrogen can cause edema of upper airway mucosa
    • Progesterone: Hypocapnia. Can also have protective effect: e.g. reduction of  REM sleep time, increase of respiratory drive…
  • Mechanical factors: low back pain, leg cramps, nocturia…
  • Snoring: (also see Study Nr.1)
  • OSAS (obstructive sleep apnea syndrome), Sleep-disordered breathing (SDB):
  • SDB may induce hypertension/preeclampsia during pregnancy.
  • Pregnancy may precipitate or worsen sleep apnea.

Nasal CPAP has been used successfully in pregnant women with OSAS. Those pregnant women who had infants of normal birth weight tended to have been treated with CPAP before the first trimester.

Sleep apnea syndrome occurs in about 4% of women, and the obese pregnant women should be screened for snoring severity, nocturnal awakening, and daytime fatigue. If present, a sleep study should be done and CPAP initiated as soon as possible if OSAS is diagnosed.

  • Restless Leg Syndrome
  • Sleep-maintenance-insomnia

3.  Sleep-Related Disordered Breathing During Pregnancy in Obese Women (Maasilta et al_ 120 (5) 1448 — Chest.htm)

Significantly more sleep-related disordered breathing occurred in obese mothers than in subjects of normal weight, despite similar sleeping characteristics. Weight gain and increased nasal obstruction during pregnancy are considered potentially detrimental, leading to sleep breathing disorders. A decrease in arterial PO2 has been noted during pregnancy when women change from a sitting to the supine position while awake, a decrease more important in obese patients.


  Apnea-Hypopnea Index (events/h) Oxygen desaturation (events/h) Snoring (%) Respiratory arousal index (events/h)
Obese 1.7 5.3 32 7.4
Control 0.2 0.3 1.1 0.8
Late preg. Increased       in        obese


Increased          in

obese significantly

Increased          in

obese significantly

Increased          in

obese significantly


4.  OSAS-in Pregnancy resulting in pulmonary Hypertension(1998-lewis.pdf)

This represents the first case in the literature of obstructive sleep apnea leading to pulmonary hypertension in pregnancy. In this case obstructive sleep apnea resulted from morbid obesity, and culminated in right-sided heart failure and pulmonary hypertension during pregnancy. The patient responded well to nasal CPAP as evident by the massive diuresis (104 Pounds!) and good maternal outcome. 2 liters of oxygen and pressures of 18 cm of water were needed to stabilize the apnea and raise the baseline saturation from 70% to 97%.

It is well documented that obstructive sleep apnea can lead to right-sided heart failure and pulmonary hypertension. Pulmonary hypertension, whatever the cause, has a high maternal mortality rate. The high volume and cardiac output state of pregnancy may exacerbate this disease process. 

5.  Inspiratory flow limitation during sleep in pre-eclampsia comparison with normal pregnant and nonpregnant women  ( Connolly et al_18 (4) 672 — European Respiratory Journal.htm)

Since OSAS has been identified as an independent risk factor for the development of hypertension, it is possible that occult disordered breathing during sleep may be a risk factor to the development of pregnancy-related hypertension, including pre-eclampsia.

Recent evidence has emerged that inspiratory flow limitation is common in patients with preeclampsia and that short-term relief of flow limitation by nasal continuous positive airway pressure (nCPAP) is associated with a reduction in nocturnal blood pressure (BP) levels in these patients.

The prevalence of inspiratory flow limitation during sleep in pre-eclamptic females was objectively assessed and compared with normal pregnant and nonpregnant females.









inspiratory              flow

limitation by flattening index in % Sleep period time

1.6 3.7 4.6 15.5 31
Arterial               oxygen


5.3 5.6 5.4 16.2 16.7


These findings suggest a possible relationship between disordered breathing during sleep and pre-eclampsia, but do not allow the authors to determine whether this finding is a causative factor or simply a consequence of the development of pre-eclampsia:

  • The generalized oedema that is associated with pre-eclampsia could conceivably cause narrowing of the upper airway and thus, predispose to inspiratory flow limitation, thereby favouring a secondary association.
  • A number of maternal factors have been reported to increase the likelihood of developing pre-eclampsia, including obesity, insulin resistance, hypertension, and elevated plasma homocysteine levels. Several of these factors are also associated with the development of OSAS.
  • Previous reports have indicated that the development of snoring in pre-eclampsia predates clinical manifestations of the disorder, which has been proposed as supportive evidence that snoring contributes to the development of pre-eclampsia.


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October 2004, 59:10 > Determination of Maternal Body…                        < Previous  |   Next >

Determination of Maternal Body Composition in Pregnancy and Its Relevance to Perinatal Outcomes.

Obstetrical & Gynecological Survey. 59(10):731-742, October 2004. McCarthy, Elizabeth A. MB BS *; Strauss, Boyd J.G. PhD +; Walker,

Susan P. MD ++; Permezel, Michael MD [S]


Three models and 10 specific methods for determining maternal body composition are discussed and their perinatal relevance reviewed. English language publications (1950 to January 2004) were searched electronically and by hand. Search terms included „body composition,“ „human,“ “ pregnancy,“ „obesity,“ „adiposity,“ „regional,“ „2-, 3-, 4component,“ „truncal,“ „peripheral,“ „central,“ „visceral“ along with specific techniques and outcomes listed subsequently. Three models of body composition are described: 2-component being fat and fat-free mass; 3-component being fat, water, and protein; and 4-component being fat, water, protein, and osseous mineral. Ten techniques of body composition assessment are described: 1) anthropometric techniques including skinfold thicknesses and waist-hip ratio; 2) total body water (isotopically labeled); 3) hydrodensitometry (underwater weighing); 4) air-displacement plethysmography; 5) bio-impedance analysis (BIA); 6) total body potassium (TBK); 7) dual-energy x-ray absorptiometry (DEXA); 8) computed tomography (CT); 9) magnetic resonance imaging (MRI); and 10) ultrasound (USS). Most methods estimate total adiposity. Regional fat distribution-central (truncal) compared with peripheral (limb) or visceral compared with subcutaneous-is important because of regional variation in adipocyte metabolism. Skinfolds, DEXA, CT, MRI, or USS can distinguish central from peripheral fat. CT, MRI, or USS can further subdivide central fat into visceral and subcutaneous. Perinatal outcomes examined in relation to body composition include pregnancy duration, birth weight, congenital anomalies, gestational diabetes, gestational hypertension, and the fetal origins of adult disease. A few studies suggest that central compared with peripheral fat correlates better with birth weight, gestational carbohydrate intolerance, and hypertension. Means of accurately assessing maternal body composition remain cumbersome and impractical, but may more accurately predict perinatal outcomes than traditional assessments such as maternal weight.

Target Audience: Obstetricians & Gynecologists, Family Physicians

Learning Objectives: After completion of this article, the reader should be able to list the various techniques of body composition assessment, to compare the various models used to estimate body composition, and to outline the clinical correlates of material body composition in pregnancy.

(C) 2004 Lippincott Williams & Wilkins, Inc.

Zuletzt aktualisiert am: 16.12.2015

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