Severity of sleep-disordered breathing improves following parturition

Study Objective: Changes in sleep-disordered breathing associated with late pregnancy have not previously been systematically investigated; however, a number of case reports indicate exacerbation of obstructive sleep apnea in late pregnancy, often in association with maternal hypertension. We aimed to compare the severity of sleep-disordered breathing and associated maternal blood-pressure responses in late pregnancy with the nonpregnant state. Design: Case-controlled, longitudinal study of sleep-disordered breathing during late pregnancy and postpartum. Study Patients: Ten women referred for suspected sleep-disordered breathing during the third trimester of pregnancy. Interventions: None. Measurements and Results: Full overnight polysomnography and continuous systemic blood pressure were measured during the third trimester of pregnancy and 3 months following delivery. Parameters of sleep-disordered breathing, including apnea hypopnea index and minimum overnight arterial oxyhemoglobin saturation, were compared between antenatal and postnatal studies. An improvement in both apnea-hypopnea index and minimum arterial oxyhemoglobin saturation occurred consistently in all subjects postnatally. In non-rapid eye movement sleep, mean apnea-hypopnea index was reduced from 63 +/- 15 per hour antenatally to 18 +/- 4 per hour postnatally (P =.03), and in rapid eye movement sleep, from 64 +/- 11 per hour to 22 +/- 4 per hour (P =.002). Minimum arterial oxyhemoglobin saturation was increased from 86% +/- 2% antenatally to 91% +/- 1 % postnatally (P =.01). Arterial blood-pressure responses to apnea peaked at 170 to 180 mm Hg antenatally, while they only peaked at 130 to 140 mm Hg postnatally. Conclusion: This study indicates that late pregnancy may be associated with increased severity of sleep-disordered breathing and associated blood-pressure responses.