SLIPP: A Multi-centre randomised trial assessing time spent in supine position during sleep in the third trimester of pregnancy with or without a position aid

This trial will test whether advice alone compared to advice and a pillow device best supports non-supine sleep using the Night Shift device as an objective measure of both sleep duration and position. This design could also be employed in the future for a roll out of sleep position interventions, but crucially the optimum intervention would need to be properly validated, which is what this trial aims to do.