Pregnancy-onset obstructive sleep apnea and ambulatory blood pressure

Study objective: Elevated nocturnal blood pressure (BP) increases the risk for hypertensive disorders of pregnancy (HDP). Though obstructive sleep apnea (OSA) increases the risk for HDP, data on OSA and 24-hour ambulatory blood pressure monitoring (ABPM) in pregnancy are scarce. We aim to examine the BP profile of women with pregnancy-onset OSA.

Methods: Pregnant women with overweight / obesity and snoring were recruited at <13 weeks gestation and underwent level III home sleep apnea testing and 24-hour ABPM at enrollment and at 31-34 weeks' gestation. Women with OSA at enrollment were excluded . Mean differences in nocturnal BP and 24-hour BP measurements, between women with pregnancy-onset OSA and women without OSA, were computed by multivariable linear regression.

Results: 40 / 101 participants had pregnancy-onset OSA (respiratory event index (REI) >5 events per hour) in the third trimester. Despite no significant differences in baseline BP, nocturnal systolic and diastolic BP were significantly higher in women with pregnancy-onset OSA compared to women without OSA, after adjusting for multiple covariates (mean difference 5.49 (1.45-9.52) and 3.89 (0.19-7.60), respectively). Differences in systolic BP persisted into the daytime in the OSA group. Lack of nocturnal dipping was highly prevalent in both groups, but the difference was not significant in the adjusted model.

Conclusion: Pregnancy-onset OSA in the 3rd trimester is associated with elevated nocturnal BP and daytime systolic BP. The lack of nocturnal dipping irrespective of REI cut-off in pregnant women at risk for SDB further demonstrates limitations of REI in defining pathology in pregnancy.