Sleep position and breathing in late pregnancy and perinatal outcomes.

Study Objectives: Body position during sleep has been related to breathing in adults with obstructive sleep apnea (OSA). While sleep-disordered breathing is common, little information is available on the relation between sleep position and maternal breathing in pregnancy. We examined associations between the supine position, maternal breathing, and perinatal outcomes.

Methods: Women with a singleton, uncomplicated pregnancy were recruited and underwent an ambulatory overnight sleep study between 33 to 36 weeks using the Watch-PAT device. Their medical records were also reviewed.

Results: A total of 148 pregnant women were recruited (mean age: 33 ± 4 years; mean body mass index: 27.6 ± 4.0 kg/m²). They spent approximately one-half of their sleeping time in a supine position. The group's mean apnea-hypopnea index (AHI) was 3.6 events/h in the supine position and 2.9, 2.6, and 2.1 events/h for the prone, right, and left positions, respectively. Median AHI and oxygen desaturation index were higher and SpO₂ nadir was lower in the supine versus nonsupine position (P < .0001, P < .0001, and P = .006, respectively). Peripheral oxygen saturation nadir was associated with the percentage of time spent sleeping in the supine position (P = .02). No correlations were found between supine sleep position and perinatal outcomes. There were no differences in the distributions of body positions between women with and those without OSA.

Conclusions: Women in the third trimester of pregnancy with or without OSA spent large proportions of sleeping time in a supine position. Supine position was associated with more respiratory events and more and deeper oxygen desaturation events. They were not associated with perinatal outcomes.

Clinical Trial Registration: Registry: ClinicalTrials.gov; Name: Fetal Outcome of Sleep Disordered Breathing During Pregnancy; URL: https://clinicaltrials.gov/ct2/show/NCT00931099; Identifier: NCT00931099.