Randomization and interventions
Randomization was stratified by trimesters with varying block sizes of 4–8. After each participant agreed to participate and signed informed consent, clinical data were entered into a centralized computer system for automatic randomization sequence generation and subsequent immediate allocation. Participants receiving CPAP initiated treatment nightly until delivery. An auto-adjusted CPAP (auto-CPAP: Phillips-Respironics REMstarAutoM®/Dreamstation®) with heated-humidification delivered via nasal mask was used throughout pregnancy with pressure range between 4 and 15 cmH