Positive Airway Pressure Treatment of Obstructive Sleep-disordered Breathing in Hypertensive Disorders of Pregnancy

Inclusion Criteria: * ≥ 18 y with a singleton pregnancy, ≥ 12 weeks' gestation * diagnosis of hypertensive disorder of pregnancy, including pre-existing hypertension, gestational hypertension and pre-eclampsia, as defined by Canadian Hypertensive Disorders of Pregnancy Working Group Criteria (Magee et al; Best Practice and Research Clinical obstetrics \& Gynaecology. 2015;29(5):643-657) * presence of obstructive sleep-disordered breathing (OSDB) on a single night in-home complete (Level 2) polysomnogram defined by an apnea-hypopnea index (AHI) ≥ 5 events/h and/or the presence of inspiratory flow limitation on ≥ 30% of breaths. Exclusion Criteria: * severe pre-eclampsia/eclampsia requiring urgent delivery * chronic kidney disease or other secondary cause of hypertension * known cardiac disease, transient ischemic attack/stroke * malignancy or other chronic medical or psychiatric condition * smoking, alcohol use, illicit drugs * current/recent treatment for sleep-disordered breathing * severe sleep-disordered breathing defined as an apnea-hypopnea index (AHI) ≥ 30/h with either severe sleepiness (Epworth sleepiness score ≥ 15) or hypoxemia (4% Oxygen Desaturation Index ≥30/h or arterial oxygen saturation (SpO2) \<80% for \>10% of Total Sleep Time)