Efforts to achieve safe sleeping positions in pregnancy via PT ought to be balanced against possible detrimental effects on the quality and quantity of sleep. A recent systematic review and meta-analysis demonstrated the clinical utility of newer generation PT devices that attach to the neck or chest and provide a subtle vibratory stimulus when the user is in the supine position . Although this review included two studies that indicated objective sleep quality parameters improved with such sleep position trainers [12,13], these studies have a small sample size, and the external validity of the meta-analysis is limited to persons with mild to moderate position-dependent obstructive sleep apnea (OSA) (the mean (standard deviation) apnea-hypopnea index was 21.8 (7.2) events per hour). Treatment with newer generation PT devices resulted in these individuals experiencing, on average, a reduction in their AHI by 11.3 events per hour; therefore, because OSA is known to disrupt sleep architecture, it is intuitive that these individuals would experience improved sleep quality (despite their sleep being intermittently interrupted by a supine alarm) as a result of a reduced AHI and, thus, OSA severity.
However, when the primary indication for PT is not to treat positional OSA, there is a paucity of data regarding the safety and efficacy of passive methods of PT in comparison to active methods (e.g., vibratory alarms). For example, if the primary indication of PT is to optimize maternal-fetal hemodynamics via the pelvis position, in the absence of positional OSA and its impact on sleep architecture, it becomes obvious that active methods of PT are more likely to disrupt sleep architecture and result in reduced sleep quality. Moreover, the authors of the meta-analysis emphasize the need for larger randomized control trials and recommend future research focus on how PT devices affect quality-of-sleep metrics including sleep fragmentation, sleep continuity, sleep stage changes as well as their effect on daytime sleepiness .
Drawing on the concept of PT for SDB, our team designed a PT device for pregnant women called the PrenaBelt™ (patent pending). The PrenaBelt™ is a belt-like device worn at the level of the pregnant woman’s pelvis. While the PrenaBelt™ does not prevent the user from lying supine during sleep, it significantly decreases the amount of time she spends in this position via the mechanism of PT [20,22].
A feasibility study done on the PrenaBelt™ to determine if it would reduce supine sleep time in the home setting in the third trimester showed that supine sleeping time can be reduced with the use of PrenaBelt™ without affecting sleep quality and duration and with added benefits in nocturnal maternal respiration and fetal heart rate pattern . Another study that investigated the use of the PrenaBelt™ by pregnant Ghanian women in their third trimester in a home setting showed that the use of the PrenaBelt™ resulted in increased birth weight and GROW centile by 100g and 7% respectively, despite a 56% adherence. For every 1% increase in adherence to using either the PrenaBelt™ or sham-PrenaBelt™, the GROW centile increased by 0.5% and this was statistically significant .