How does pregnancy impact sleep apnea over time?

Impact of Pregnancy on Sleep Apnea Over Time

Pregnancy significantly worsens sleep apnea over time due to physiological and anatomical changes, with the highest risk occurring during the second and third trimesters when respiratory symptoms typically intensify. 1, 2

Physiological Changes During Pregnancy That Impact Sleep Apnea

Pregnancy creates multiple conditions that can either unmask existing sleep apnea or exacerbate it:

• Weight gain: Pregnancy-related weight gain increases pharyngeal fat deposits, decreasing pharyngeal patency and worsening OSA 1
• Hormonal changes: Estrogen causes mucosal edema and vasomotor rhinitis
• Anatomical changes:
  • Enlarging uterus elevates the diaphragm
  • Decreased functional residual capacity
  • Increased oxygen consumption (up to 20%)
  • Upper airway narrowing due to fluid retention

Progression of Sleep Apnea Through Pregnancy

The impact of pregnancy on sleep apnea follows a distinct pattern:

• First trimester: Relatively fewer exacerbations and respiratory symptoms 1
• Second and third trimesters: Significant increase in sleep apnea symptoms and severity 1, 3
• Last month of pregnancy: Some reduction in symptoms 1

Risk Factors for Sleep Apnea During Pregnancy

Certain factors substantially increase the risk of developing or worsening OSA during pregnancy:

• Pre-pregnancy obesity: The strongest predictor, with 15-20% of obese pregnant women developing OSA 2
• Excessive gestational weight gain: Each 10% increase in body weight increases OSA risk six-fold 1
• Comorbidities: Pre-eclampsia, gestational diabetes, and gestational hypertension 3

Maternal and Fetal Consequences

Untreated sleep apnea during pregnancy is associated with significant adverse outcomes:

• Maternal risks:

  • Increased risk of pre-eclampsia 3, 4
  • Gestational diabetes 4
  • Gestational hypertension 5
  • Cardiomyopathy and congestive heart failure 4
  • Pulmonary embolism 4
  • Increased in-hospital mortality 4

• Fetal risks:

  • Low birthweight 5
  • Preterm delivery 3
  • Intrauterine growth restriction 5
  • Potential long-term developmental issues 3

Post-Pregnancy Considerations

Sleep apnea symptoms often persist after delivery:

• Women with pregnancy-onset OSA remain at higher risk postpartum 4
• Respiratory monitoring is recommended during the immediate postpartum period due to risk of respiratory suppression 4
• Weight retention after pregnancy may contribute to persistent OSA 1

Clinical Implications

The current evidence suggests that:

1. Sleep apnea screening should be considered for all pregnant women, especially those with obesity or other risk factors 3
2. The natural course of OSA during pregnancy tends toward worsening, particularly in the second and third trimesters 1
3. Spontaneous improvement of OSA during pregnancy cannot be expected 1
4. Treatment with CPAP should be considered, though more research is needed on treatment outcomes 6, 4

Common Pitfalls in Management

• Misattribution of symptoms: Fatigue and sleep disruption may be attributed to normal pregnancy rather than sleep apnea
• Inadequate screening: Current OSA screening tools may not perform well in pregnant populations 6
• Delayed treatment: Waiting for severe symptoms before intervention may increase maternal and fetal risks
• Postpartum discontinuation: Assuming OSA will resolve completely after delivery

In conclusion, pregnancy represents a vulnerable period for the development or worsening of sleep apnea, with a clear pattern of progression throughout gestation. The condition requires vigilant monitoring and appropriate intervention to mitigate the significant maternal and fetal risks associated with untreated sleep-disordered breathing during pregnancy.