Introduction

Sleep-disordered breathing (SDB), characterized by specific underlying physiological mechanisms, involving obstructive and central pathophysiology, affects nearly 1 billion individuals worldwide, and is associated with excessive cardiopulmonary morbidity. Obstructive sleep apnea (OSA) is marked by repetitive upper airway obstruction despite ongoing respiratory effort, whereas, central sleep apnea (CSA) is uncommon and defined by the episodic cessation of airflow without respiratory effort. Recognition of sleep-disordered breathing during pregnancy has evolved significantly over the past two decades. As evidence mounts regarding the association between SDB and adverse maternal-fetal outcomes, early identification and intervention have become increasingly vital components of prenatal care.

This article reviews SDB in pregnancy including epidemiology, pathophysiology, and clinical manifestations, and risk factors, impact of maternal and fetal outcomes, diagnosis, and management for this specific population.

Epidemiology

Estimates of the prevalence of SDB during pregnancy vary widely. Studies using objective measurements report rates ranging from 3% in early pregnancy to 26% in the third trimester. When relying solely on self-reported symptoms like habitual snoring, prevalence rates can be even higher.

One large prospective study found that self-reported snoring increased from 11% in the first trimester to 28% by the third trimester. Objective assessments using polysomnography revealed that the apnea-hypopnea index (AHI) similarly worsens with gestational progression.

Risk factors for developing SDB during pregnancy mirror those in the non-pregnant population but are intensified by gestational physiological changes.

Pathophysiology

The pathophysiology of sleep-disordered breathing in pregnancy is multifactorial, involving anatomical, hormonal, and physiological changes that increase upper airway collapsibility and reduce respiratory reserve. Elevated estrogen and progesterone levels during pregnancy lead to hyperemia and edema of the upper airway mucosa, increasing airway resistance and narrowing the pharyngeal lumen. This is compounded by weight gain and fluid retention, which further reduces upper airway patency and increases neck circumference, especially in the third trimester.

Pregnancy also reduces functional residual capacity and residual lung volume due to the upward displacement of the diaphragm due to the enlarging uterus, which decreases oxygen reserves and increases the risk of hypoxemia during apneic events. Increased ventilator drive and metabolic rate, along with higher oxygen consumption, further stress the maternal respiratory system. These changes are particularly pronounced in women with additional risk factors such as obesity, advanced maternal age, or pre-existing hypertension.

The resulting intermittent hypoxia and sleep fragmentation can trigger oxidative stress, systemic inflammation, sympathetic activation, and endothelial dysfunction, which are implicated in the development of gestational hypertensive disorders and gestational diabetes. Pathophysiology is thus a complex interplay of upper airway anatomical changes, altered respiratory mechanics, and systemic metabolic and vascular responses unique to pregnancy.

Risk factors for Sleep-Disordered Breathing in Pregnancy

The most important risk factors for developing sleep-disordered breathing during pregnancy are:

Pre-pregnancy obesity and higher baseline body mass index (BMI): Obesity is the strongest and most consistent risk factor, with prevalence of obstructive sleep apnea (OSA) reaching 15- 20 % in obese pregnant women and increasing with higher BMI.

Excessive gestational weight gain: Weight gain during pregnancy further increases upper airway collapsibility and risk of SDB.

Advanced maternal age: Older pregnant women at higher risk, independent of BMI.

Pre-existing hypertension or history of preeclampsia: These comorbidities are associated with increased SDB risk and may also be consequences of SDB.

Anatomical and physiological changes of pregnancy: Hormonal changes (elevated estrogen and progesterone), fluid retention, and upper airway edema contribute to airway narrowing and increased SDB risk, especially in the third trimester.

Multiparty: Some studies suggest that women with multiple prior pregnancies may have increased risk, possibly due to cumulative effects on weight and airway anatomy.

Habitual snoring or witnessed apneas: New-onset or worsening snoring during pregnancy is a clinical marker for increased SDB risk.

These risk factors interact with the pathophysiological changes of pregnancy such as reduced functional residual capacity, increased ventilator drive, and upper airway edema to increase the likelihood and severity of SDB as pregnancy progresses.

SDB Impact on Maternal and Fetal Outcomes

There is a growing body of evidence which links untreated SDB with several serious maternal and fetal complications. Maternal outcomes include pre-eclampsia and gestational diabetes. Studies suggest a 2- to 3-fold increased risk for preeclampsia with intermittent hypoxia triggering endothelial dysfunction, oxidative stress, and sympathetic nervous system over activity. Sleep fragmentation impairs glucose metabolism which could lead to gestational diabetes. One prospective study reported a nearly 3-fold higher risk of GDM among women with OSA. Elevated rates due to labor arrest, fetal distress increase the risk of cesarean delivery and although rare there is the possibility of cardiomyopathy which could potentially be catastrophic.

Fetal and Neonatal Outcomes include intrauterine growth restriction (IUGR) due to chronic maternal hypoxemia reducing placental perfusion. Pre-term birth rates have been reported in multiple observational studies. Low Apgar scores and NICU admissions have been reported in infants born to mothers with untreated SDB having poorer short-term outcomes.

Clinical Manifestations

The signs and symptoms of SDB during pregnancy are often nonspecific and can mimic normal pregnancy-related changes, making clinical recognition challenging. Several common symptoms have been identified. They include loud, habitual snoring (reported by partners), witnessed apneas or choking episodes during sleep, excessive daytime sleepiness, not fully explained by pregnancy alone, morning headaches, cognitive impairment (“pregnancy brain”), gastroesophageal reflux disease (GERD) exacerbations, and frequent nocturia (beyond normal pregnancy frequency)

Patients with more severe disease may experience excessive fatigue impacting daily functioning, increased risk of motor vehicle accidents, and significant mood disturbances.

Diagnosis

Several Screening Tools are available for use in diagnosing SDB. Common screening questionnaires include: the STOP-BANG, which has been adapted for pregnancy but not fully validated, the Berlin Questionnaire, and the Epworth Sleepiness Scale (ESS). New pregnancy-specific tools, such as the Facco Pregnancy Sleep Questionnaire have been developed to improve sensitivity.

Polysomnography (PSG) remains the gold standard for diagnosing SDB with Home Sleep Apnea Testing (HSAT) also available. The HSAT is a practical alternative but is less sensitive in pregnancy, particularly for mild disease and non-obstructive patterns. The diagnostic criterion for use is AHI ≥5 events per hour with severity grading as: mild range from 5-15 AHI, moderate range between 15-30 AHI and severe range as >30 AHI. Some experts advocate for lower diagnostic thresholds in pregnancy due to the potential for even mild hypoxemia to impact fetal well-being.

Management

Management of Sleep Disordered Breathing (SDB) in pregnancy focuses on symptom relief, maternal-fetal safety, and minimizing adverse outcomes. Treatment should be individualized based on severity and gestational age.

Lifestyle modification is the first-line management recommendation for mild cases of SDB. Recommendations include patient counseling on appropriate gestational weight gain per IOM guidelines, encouraging lateral sleeping (especially left side) to reduce airway obstruction and aortocaval compression, avoiding sedatives/alcohol as they worsen upper airway muscle tone and using a nasal decongestion such as saline sprays or nasal strips to improve airflow.

In moderate to severe SDB/) SA the gold standard for management is continuous positive airway pressure (CPAP). This improves oxygenation, reduces blood pressure, and may lower the risk of pre-eclampsia and gestational hypertension. CPAP is safe during all trimesters although adherence can be challenging with the suggestion of considering heated humidifiers and mask adjustments.

Surgery

Although one study used tracheostomy, which resolved SDB, no kind of surgery is preferred as a treatment option for SDB because it increases the risks of adverse outcomes. If electing surgery for SDB management the use of a multi-professional team consisting of an obstetrician, sleep specialist, and anesthesiologist should be considered. Anesthesia planning is crucial as SDB is a risk factor for difficult intubation and postoperative respiratory events. Pregnant women with diagnosed or suspected SDB represent a high-risk group for anesthesia during labor, delivery, and any surgical procedures. Anesthesia considerations must include airway management due to airway edema, sedation sensitivity due to respiratory depressant effects, and/or postoperative monitoring for hypoxemia and obstructive events. A regional anesthetic such as an epidural is generally preferred over a general anesthesia when feasible.

When surgery is elected for patient management, close monitoring of maternal fetal outcomes is also essential. Regular blood pressure monitoring (due to link between SDB and preeclampsia), screening for gestational diabetes, and fetal surveillance if severe SDB or comorbidities are present is recommended.

Conclusion

Sleep Disordered Breathing is a prevalent and often underdiagnosed condition with significant health consequences. Its spectrum ranges from simple snoring to severe obstructive and central sleep apnea, affecting individuals across all age groups, including pregnant women. Early recognition and intervention are essential to prevent cardiovascular, metabolic, and neurocognitive complications. Diagnostic tools like polysomnography and effective treatments such as CPAP therapy, weight management, and lifestyle modifications can greatly improve patient outcomes and quality of life. Increased awareness among healthcare providers and patients is crucial to ensure timely diagnosis and comprehensive care.

Case Studies

Case 1: Mild SDB and Gestational Hypertension

A 29-year-old woman, BMI 34 kg/m², presents at 24 weeks gestation with new-onset snoring and daytime fatigue. Sleep study reveals mild OSA (AHI 8). CPAP is initiated. Her blood pressure stabilizes, and she delivers a healthy infant at 39 weeks.

Teaching point: Early CPAP therapy may stabilize blood pressure and improve pregnancy outcomes.

Case 2: Severe SDB and Emergency Cesarean Section

A 36-year-old woman with pre-pregnancy obesity (BMI 42) and chronic hypertension is found to have severe OSA (AHI 45) at 30 weeks gestation. Despite CPAP therapy, she develops severe preeclampsia requiring preterm cesarean at 34 weeks.

Teaching point: Severe SDB may contribute to preeclampsia despite optimal therapy.

Conflicts of interest

In compliance with the ICMJE uniform disclosure form, all authors declare the following:

Payment/services info

All authors have declared that no financial support was received from any organization for the submitted work.

Financial relationships

All authors have declared that they have no financial relationships.

Other relationships

All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.