The Back-Off Study: Evaluating the Prenabelt 2

June 29, 2021
Print Friendly, PDF & Email

This presentation will first outline how and why the Prenabelt 2 was developed. Then the study methodology will be outlined viz that the study was a 6-night in-home study in late pregnancy involving 10 pregnant women. Results of the effectiveness of the device to avoid supine sleep will be shared as well as qualitative data from the participants regarding their experiences with the new device.

Dr Jane Warland is the recently appointed professorial lead (midwifery) at Curtin University / King Edward memorial Hospital Perth Western Australia. She has an extensive track record in Stillbirth research. In the past few years she has focussed her research on stillbirth prevention strategies including going to sleep position and how to best promote lengthy side sleeping in late pregnancy.

Dr. Warland has disclosed that she does not have any real or perceived conflicts of interest in making this presentation.

Joslyn DeBoode: Dr Jane Warland is the recently appointed professorial lead, midwifery, at Curtin University, King Edward Memorial Hospital, Perth, Western Australia. She has an extensive track record in stillbirth research. In the past few years she has focused her research on stillbirth prevention strategies including going to sleep position and how to best promote lengthy side sleeping in late pregnancy. Dr. Warland’s presentation is titled, The Back-Off Study: Evaluating the PrenaBelt 2.

Dr. Jane Warland: Hi. I’m Jane Warland, and I’d like to thank the Star Legacy Foundation for the opportunity to talk about the Back-Off Study today. I’m just going to share my screen. The Back-Off Study was evaluating the PrenaBelt 2. An overview of the particular study, we looked at why sleep position in pregnancy might matter and how positional therapy might help or not? I’d like to also summarize positional therapy research to date more generally, and what’s new in positional therapy in pregnancy, and then talk a little bit about where to from here.

This all started way back in 2010 when Tomasina Stacey published the results of her PhD study, which showed that there may be a correlation between sleep position and poor pregnancy outcome. This was preliminary analysis, obviously early days, and it was thought that this needed to be validated before we passed this information onto pregnant women. For the next 10 years or so there have been a series of studies which have looked to confirming or not Tomasina’s earlier findings.

This has all culminated in all of those particular studies, leads getting together and sharing their data to the point where we now have significant numbers of cases and controls which together are pointing to findings that supine going to sleep position is independently associated with late stillbirth. We now have enough numbers to confirm that going to sleep on your side left or right appears to be equally safe, and that there are actually no significant interactions with fetal vulnerability. Therefore, supine going to sleep position is a contributing factor for late stillbirth in pregnancy. Importantly, they showed that if every pregnant woman in the world went to sleep on her side in late pregnancy, that about 6% of stillbirths could be prevented by just taking that one simple measure.

This aligns very nicely with the triple risk in pregnancy model, which is looking at the interaction between fetal stresses and placental or fetal vulnerability and maternal factors. A fetal stressor might be inferior vena cava compression, maternal factors might have an interplay there with age, obesity, parity, sleep-disordered breathing, supine sleep, all being factors which might contribute. Altered fetal activity, particularly, and fetal growth restriction being things that indicate that the fetus might be vulnerable to stillbirth.

Also from New Zealand, there’s been a significant amount of work looking at, if you talk to pregnant women about setting to sleep on their side, can they do it? Do they want to do it? Are they aware that it’s important to do it? This particular study, which was recently published in BMJ Open showed that, yes, pregnant women do receive and do implement sleep onside advice without difficulty or concern. Although some groups of women might need a tailored approach, particularly if they have English as a second language, for example.

But, and it’s a fairly big but, all of the preceding studies that I’ve just talked about are reliant on maternal report of sleeping position and intention to sleep on the side rather than it being confirmed that the woman actually was sleeping on the side when she said she was. The one study which has looked at accuracy of self report of sleep position in late pregnancy was one that I did with Jill Dorrian a few years ago now where we asked 30 women to settle to sleep on their left, which was the side of choice at that stage. We reported a fairly good correlation between diary reported and video determined indicator of sleeping position with an average difference of only three minutes between these two reports, self-report and video report. That might suggest that the women are pretty accurate, but there was wide disparity between the diary and the video for the average to be only three minutes. Some women were incredibly inaccurate and others were very accurate.

We also looked at the fact that most women seemed to be able to comply with instruction to go to sleep on their left, in that the position that they reported going to sleep in was the one that the video camera actually said that they had gone to sleep in.

But, for those who did not ordinarily sleep on their side, we asked participants to sleep on their left and that might result in reduced sleep duration and also sleep quality. Both of those things are incredibly important in late pregnancy, not only to prevent stillbirth, but also for maternal and fetal wellbeing more generally than that.

Looking at positional therapy was first thought of as an idea back in World War I when soldiers in the trenches were instructed to wear their backpacks to go to sleep so that they didn’t snore so that their snoring wouldn’t alert the enemy as to where they were. That’s the Genesis, I guess, of positional therapy. Since then it’s moved to a range of different devices, which are all based on this concept of, if you put something on the person’s back, then you might prevent them from sleeping on their back. This can be as simple as sewing a tennis ball into your back or wearing something that looks still pretty much like a backpack still where to bed or having a belt, which is pretty much going across the back horizontally.

We have to think about whether pregnancy pillows are a form of positional therapy, and I would suggest not. Each of these look like they have the potential to act to keep the woman off her back, but in actual fact each of them is perfectly possible to sleep between the pillows flat on your back. And so none of these actually live up to the claim of keeping you sleeping on your side.

Positional therapy in pregnancy was developed by Alan Kember, and he has called this device a PrenaBelt. It’s based on the same principles as I showed you before. However, the position is particularly looking at pelvic position rather than position of the chest. The PrenaBelt is worn around the lower abdomen in order to achieve positional therapy with keeping the woman off her back.

It’s been tested in three clinical trials in Australia, Canada, and Ghana, and we’ve reported from each of those trials that the PrenaBelt is actually effective in reducing time spent sleeping supine, which is good. It also has maternal and fetal benefits in that the mother has less oxygen desaturations and better oxygen saturation, and the baby has fewer heart rate deceleration when the mother is wearing the PrenaBelt than when she’s not.

We also know that the PrenaBelt has minimal effect on maternal perception of sleep quality which is incredibly important in late pregnancy as I said before, and also that we objectively established sleep time via another device that you don’t see there, but it’s measuring sleep time objectively and PrenaBelt didn’t have any effect on the length of time that the woman was actually comfortably sleeping, which is also good. The Ghana trial, unfortunately, didn’t find a statistically significant effect on birth weight, which is what the main objective of that particular study was.

The PrenaBelt is trying to achieve inferior vena cava compression relief and that has been shown to be demonstrable around 12.5 degrees to 15 degrees of lateral tilt. This means that if you achieve 15 degrees of tilt, that you probably are significantly reducing the effect of inferior vena cava compression. Some women might still be susceptible, and even at those levels have vena cava compression, but most will be significantly relieved at 15% of tilt. We can generally say that 15% is needed to reliably reduce inferior vena cava compression, and it’s important to realize that 15% tilt is nothing like lying completely on one side or the other. It really is quite literally a 15% tilt.

The Back Off Study was funded by the Academy of Technology and Engineering Global connections fund. The aim of the fund was to establish collaborations between Australian universities and overseas startup businesses. It was quite ideal to seek and gain that funding as that’s exactly who we are.

We developed the PrenaBelt further and decided that rather than having an inbuilt positional therapy, that we would attach it via Velcro, the built itself is extremely supportive, is quite stretchy, very comfortable to wear, and as you can see in the top left photo, that’s the new balls PrenaBelt. The next photo next to it is a device called the Ajuvia, which the woman sticks just above her bikini line, which gives us body position. We also used a security camera which gave us the mother’s position when she moved. Rather than looking at eight hours of video with her lying still, we looked at 20 minutes of video with her moving from one position to another. Then the attachments that are new to the PrenaBelt that we were also assessing.

The Back Off Study was a six night in-home study with women between 28 and 36 weeks pregnant. We aimed to recruit 10 women because we were using within a group and a crossover randomized design, meaning that each of the women apart from the first night, which was a control night, looking at how the Ajuvia matched up with the gold standard of camera. The rest of the nights were randomized to her wearing a different device in different orders so that we could be sure that we were observing the effect of the particular new attachment rather than anything else that might be measured.

The study was registered with, so you can read more about it looking up that number down there.

What have we found so far? Well, unfortunately, given COVID and a range of other circumstances, we have 4 of the 10 completed at the moment. We haven’t got a real lot to report, but early results are extremely promising. We have achieved a 15-degree tilt with these devices in general. A couple of them not as efficient as others in achieving that. Some of them you’re going right up to 30 degrees and still not seeing women on their backs. That’s really good early preliminary data.

Participant comments that we’ve got are that the belt is helping comfortable side sleep, which is the whole point of the whole thing, and also support for back, which is also really important in late pregnancy. We also asked questions about anxiety as it seems to be something that people worry about all the time in this field, and we already have participants saying that they feel empowered with the information about safe sleep in pregnancy.

Where to next? I think that it is important to realize that the research in this area isn’t done simply because we know that supine sleep position is related to stillbirth, we shouldn’t stop there. That there are a host of other things that we need to know, not the least of which is that we still don’t really understand why sleep position in pregnancy is important. We have hypotheses, but really nothing that’s proven one way or another.

We also don’t know how much supine sleep is needed to cause harm, if there’s a dose response or not. We don’t know if some women need to be more concerned than others, perhaps because their babies are more vulnerable than others. Do women who have a growth restricted baby, for example, need to be particularly concerned about having to sleep on their side? We don’t know that. Is there an interaction between sleep positions, stage of sleep and fetal response, particularly if the mother is in REM sleep? Does that impact on the fetus?

In sum, settling to sleep is important for fetal wellbeing. The position that you go to sleep in is important. Many women successfully use pillows to support comfortable side sleep, but pillows actually do not act as positional therapy, and so some women might lose their pillow in the bed. It end up on the floor, end up onto their partner’s head, a range of different spots where the pillow could end up.

Some women in pregnancy are vulnerable to stillbirth. We know that. And so they may benefit from using a positional therapy device which is attached to them that can’t move away from them while they’re sleeping, that can’t fall on the floor, and that they can’t still. The PrenaBelt is an effective means to help women avoid supine sleep in late pregnancy. As a result, stay tuned, they will be coming soon to a store near you.

Thank you for your attention. I want to acknowledge the team in Canada, my wonderful research assistants, both in Adelaide and Perth, the University of South Australia for their support in applying for the Australian Academy of Technology and Engineering grant. Thank you very much for your attention, and thank you once again to Star Legacy for the opportunity to share this research.

This presentation was part of the Stillbirth Summit 2021.   This individual lecture will be awarded .5 hours of continuing education credit to include viewing the lecture and completing evaluation and post-test.  Once received a certificate will be emailed to the address you provide in the post-test.  If you did not register for the Summit WITH Continuing Education, you can purchase the continuing education by clicking here.  This purchase will provide you access to all Stillbirth Summit 2021 lectures including continuing education credit. There is no charge for viewing the presentation.

To receive continuing education credit for this lecture, the participant must complete the evaluation and post-test

Please feel free to ask questions of the presenter.  We will obtain their answers/comments and provide them here as received.  


Share via
Copy link