Fig. 1

Consort flow diagram for screening, randomization, and follow-up analyses. CPAP continuous positive airway pressure; GA gestational age; OSA obstructive sleep apnea; RDI respiratory disturbance index (events/hour). All participants were initially enrolled only in the 1st trimester. Diagnosis of obstructive sleep apnea involved full-night, type-2 polysomnography (SomnoTouchResp®) during 1st trimester (GA < 16 weeks). Second polysomnography during 2nd trimester (GA 24–28 weeks) was repeated in participants if their 1st trimester RDI was < 5 events/hour. Participant with RDI between 5 and 29.99 events/hour at either testing were randomized. Only participants that had delivery outcomes were included in the modified intention-to-treat analyses