Halifax PrenaBelt Trial

Back and right-sided sleeping position in pregnant women has recently emerged as a potential risk factor for low birthweight (LBW) and stillbirth (SB) in the medical literature. Assuming that sleep position in pregnant women is modifiable, the same literature has indicated that this risk factor is modifiable; however, there is no evidence that this risk factor is truly modifiable.

The proposed link between back and right-sided sleeping position in a pregnant woman and LBW and SB of her baby is multifactorial; however, it ultimately implicates the woman's body position in causing compression of one of the large veins that brings blood back to her heart. This compression, along with other factors relating to the woman, her placenta, and her developing fetus, may result in decreased blood flow (nutrition and oxygen) to her developing baby, which, depending on the extent and duration, could result in LBW or SB of her baby. If the back sleeping position during pregnancy has a causative role in LBW and subsequently SB, the literature indicates that up to 17% of LBW and consequently 26% of SB could potentially be prevented by changing position to avoid back sleep. Note that 20 million LBW and 2.6 million SB occur each year worldwide.

Positional therapy (PT) is a safe and effective intervention for preventing people who snore or people who's breathing pauses during sleep from sleeping on their back - a position that makes their condition worse. The most basic form of PT modifies a person's sleeping position by either:

* Preventing them from sleeping on their back through restricting their movement, or
* Rather than restricting movement, significantly reducing the amount of time they spend sleeping on their back by applying pressure points to their body while they are on their back, which eventually causes them to shift into a different position and avoid lying on their back.

The purpose of this study is to evaluate the ability of a PT intervention to modify the position of pregnant women from their back and right side to their left side while they sleep in late pregnancy.

This study will help determine whether this potential risk factor is modifiable by way of a PT intervention, and whether it is feasible to intervene to reduce or prevent back and right-sided position sleep in late pregnancy. Demonstrating that the sleeping position of pregnant women can be modified through use of a simple, inexpensive PT intervention may be one of the keys to achieving significant reductions in LBW and late SB rates in Canada and worldwide.

The utility of the PrenaBelt in modifying maternal sleeping position and the effect of the PrenaBelt on maternal respiratory and cardiovascular parameters during sleep and sleep staging in the third trimester of pregnancy will be evaluated via a two-night, randomized, cross-over, sham-controlled, triple-blind, sleep study in third trimester pregnant women.

Two nights: one night with a positional therapy (PT) device and one night with sham-PT device to determine treatment effect on outcomes.

Randomized: participants will be randomized to treatment order: sham-PT on first night, then PT on second night, or vice versa. This will avoid the potential impact of changes to sleep across the two nights resulting from familiarization with the equipment, which could bias the results.

Cross-over: on the second night, each participant will be crossed over from PT to sham-PT (or vice versa, depending on randomization order) to allow each participant to act as her own control for comparison of treatment effect on outcomes.

Sham-controlled: a sham-PT device that has the same fit and form of the PT device but without the ability of function (pressure points) will be used as a control. The purpose of a sham-PT device is to identify any specific benefit of one element of a PT device (e.g., fit or form) above and beyond all benefits that might be attributed to everything else about that device (e.g., function). Note that there is no established effective therapy for the population for the indication under study.

Triple blind: participants, sleep technologists monitoring and scoring the sleep tests, and the specialized sleep physician reviewing and reporting the sleep test results will be blinded to the intervention received each night.

Laboratory: conducting this study in a controlled lab setting will allow for continual, real time monitoring of various cardiovascular, respiratory, and sleep parameters of each participant by the sleep technologist. This contributes to a more controlled and safer study overall.

Sleep test: body position, various cardiovascular and respiratory parameters, and sleep parameters will be continuously recorded while the participants are sleeping. Sleep lab procedures will be followed by the personnel conducting, scoring, reviewing, and reporting the sleep tests from participant preparation through discharge

Eligibility Criteria:
Inclusion Criteria:

* ≥18 years old
* low-risk singleton pregnancy
* in the last trimester of pregnancy (≥28 weeks of gestation)
* residing in the Halifax Regional Municipality

Exclusion Criteria:

* BMI ≥ 35 at booking (first antenatal appointment for current pregnancy)
* pregnancy complicated by obstetric complications (hypertension \[pre-eclampsia, gestational hypertension, chronic hypertension\], diabetes \[gestational or not\], or intra-uterine growth restriction \[\<10th %ile for growth\])
* sleep complicated by medical conditions (known obstructive sleep apnea, known to get \<4 hours of sleep per night due to insomnia, or musculoskeletal disorder that prevents sleeping on a certain side \[e.g., arthritic shoulder\])
* multiple pregnancy
* known fetal abnormality
* non-English speaking and reading