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In this episode I talk about the updated research evidence on using membrane sweeping or membrane stripping for inducing labor. Is membrane sweeping effective? What are the advantages and disadvantages? Why do some providers perform membrane sweeping without asking your permission beforehand? We talk about all of this, and more, in this latest episode of the Evidence Based Birth® podcast!

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Rebecca Dekker:

Hi, everyone. On today’s episode, we’re going to talk about the updated pros and cons of membrane sweeping.

Welcome to the Evidence Based Birth® podcast. My name is Rebecca Dekker, and I’m a nurse with my PhD and the founder of Evidence Based Birth®. Join me each week as we work together to get evidence-based information into the hands of families and professionals around the world. As a reminder, this information is not medical advice. See ebbirth.com/disclaimer for more details.

Hi, everyone. On today’s episode, I’m so excited to share with you the updated research evidence on the pros and cons of membrane sweeping. So if you’ve been listening to the podcast this year, we’ve been publishing one episode per month about the evidence on different natural induction methods. We’ve wrapped up that series, and today, I’m going to move on to a more medical method of induction. But it’s one that’s done without the use of medications or pharmaceuticals, and that method is called membrane sweeping or membrane stripping. Before I get started, I want to give you a heads up about a really fun project we’ve been working on. In past years, we’ve published a pocket guide to comfort measures in labor that we print and make available at limited times, usually right before the holidays.

Well, all summer, we’ve been working on a brand new pocket guide, and it’s called The Pocket Guide to Induction. This pocket guide is one of my most favorite projects I’ve ever worked on. It’s a small, laminated guide that fits in a scrub pocket and it’s on a key ring, and it condenses the evidence on induction into bite-size segments. The amazing thing about the new pocket guide on induction is that it has three important sections. The first section covers the evidence on the different reasons people are offered labor induction by their provider. The second section covers all of the evidence on the different methods that are used in hospitals to induce labor. And the third section covers all of the evidence on the different natural methods that can be used to induce labor.

And then it concludes with tips and tricks for navigating a labor induction and includes a password-protected page that has all of the scientific references. This pocket guide will be available starting the third week of November and we’ll do a limited time printing run of the pocket guide at that time. If you want to get on the waitlist to get one of these pocket guides, just go to evidencebasedbirth.com/waitlist. That’s all one word, evidencebasedbirth.com/waitlist, and you can be among the first to be notified when the pocket guide is available. There will be limited quantities available since it’s quite a job to put these pocket guides together and assemble them. We’ll also have some comfort measures pocket guides available for those of you who’ve been wanting one of those and haven’t been able to get one.

So now let’s move to our topic for the day, and that is membrane sweeping. Membrane sweeping is a mechanical method of labor induction. Mechanical methods are drug-free methods that involve the use of hands or medical devices to promote labor. I’m going to talk more about other mechanical methods next month. But this month I thought we would focus in on membrane sweeping because it’s extremely common. Membrane sweeping is also referred to as membrane stripping or the stretch and sweep of the membranes. It involves the care provider inserting one or two gloved fingers into the vagina and through the cervix, and then using a continuous, circular, sweeping motion to gently separate the bag of water that surrounds the baby from the lower part of the uterus.

Now, sometimes when they insert their fingers, they find that the cervix is closed or not dilated. In that case, the provider can then massage the cervix with their finger for a similar effect. This procedure is very common. About one in three pregnant people in the US says that their provider used it with them. So why might someone have membrane sweeping? Well, membrane sweeping is performed to increase your body’s natural or endogenous release of hormones that contribute to cervical ripening or the softening of your cervix, including prostaglandins and other hormones that are released. The stretching of the cervix during the procedure may also cause the release of oxytocin.

So when providers are doing this, they’re hoping that they’ll help soften and ripen the cervix and perhaps even promote uterine activity that will lead to contractions and labor and help avoid a more formal medical induction of labor later on. Membrane sweeping can be performed with consent during a vaginal exam or cervical check and does not require you to be in the hospital, so it can be done outpatient. It can be done one time or many times during the last weeks of pregnancy. So what is the evidence on the effectiveness of membrane sweeping? Well, we now have an updated Cochrane review by Finucane et al., published in 2020. In it, they combined 44 randomized trials that have compared membrane sweeping to either no treatment or sham or fake membrane sweeping or to other medications.

So when we look more closely at these 44 randomized trials, 34 of the studies had detailed info on how they performed a membrane sweep. In particular, 14 studies said that if the cervix was closed, they did cervical massage instead of a membrane sweep. So in those 14 studies, the “membrane sweeping” could actually either be cervical massage or membrane sweeping. The size of the studies ranged from 50 participants to 377 participants. The studies took place all over the world, including many studies in the United States, but also there were studies from India, Thailand, Nigeria, the United Kingdom, Canada, and many other countries. Now, knowing whether or not the people in each study were having their first baby is important when you’re looking at the data. This is called parity.

Some of the studies had only first-time parents. Others included only multiparous people, meaning that these were parents who were having a subsequent baby. But most studies had mixed parity, meaning that they had both first-time parents and multiparous people in the study. The gestational age at which membrane sweeping was performed was different in the studies as well. A few studies looked at membrane sweeping starting at 36 or 37 weeks, but most did not perform membrane sweeping until at least 38 weeks and many waited until 40 weeks. About half of the studies took place in the 1990s and the other half took place in the 21st century. For the most part, the Cochrane reviewers judged that the studies that they included were either at low risk or unclear risk for bias.

However, in general, there was a high risk of bias for performance bias due to the fact that all 44 studies did not do any masking in the study. This is sometimes called blinding. Masking would mean that clinicians and researchers did not know who was receiving which treatment, either the actual treatment or the no treatment or the placebo or sham. When no masking is used, as with all of these studies, this may lead to performance bias in which clinicians may be biased towards giving better care to the treatment group in hopes that the treatment will be shown to be effective. For example, if a provider knew someone was in the treatment group for membrane sweeping, they might delay scheduling a formal induction in hopes that the person in the treatment group will go into spontaneous labor on their own.

Now, in general, with some obstetric research studies, it is difficult and sometimes impossible to mask everyone to what’s going on, who’s getting what treatment. But there are some steps you could take. You could mask all of the other providers or the other clinicians or the researchers as to what’s going on. But unfortunately in all of these studies, everybody knew who was in the treatment group and who was not in the treatment group. Now, of the 44 studies, 40 of them compared membrane sweeping with either sham or what we call fake membrane sweeping, in which they don’t actually do the procedure but they pretend to, or no treatment. The remaining four studies compared membrane sweeping with other medications.

17 of the 40 studies looked at the effects of membrane sweeping on spontaneous onset of labor. The combined data from these trials show that pregnant people who were assigned to membrane sweeping, or cervical massage if the cervix was closed, were on average more likely to have labor start on its own instead of with a formal induction. These findings appear to apply equally to first-time parents and to those who had given birth before. 16 studies reported on whether or not the patients needed to have an induction of labor. They found that people in the membrane sweeping group were less likely to have an induction. Post-term pregnancy is the most common reason for induction, so membrane sweeping could potentially reduce inductions for post-term pregnancy.

However, the author said that these findings should be interpreted with caution because the evidence is low certainty. And again, these findings appear to apply equally to first-time parents and to those who have given birth before. When the Cochrane reviewers looked at other outcomes, they found no differences between the groups in the rate of cesareans, the use of forceps or vacuum to assist with the delivery, or serious illness or death for mothers or babies. There is less data on whether or not membrane sweeping or cervical massage can help ripen the cervix or soften the cervix. In one randomized trial, 165 participants with low Bishop’s scores, meaning they had unripened cervix at 41 weeks and four days of pregnancy, were randomly assigned to membrane sweeping, cervical massage only, or no treatment.

Only one participant assigned to membrane sweeping was not able to complete the procedure because of a closed cervix. Both the cervical massage and the membrane sweeping groups were linked to a significant increase in the average Bishop score 48 hours after the treatment compared to the control group. This is evidence that cervical massage may be an effective alternative to membrane sweeping and could be offered to pregnant people with a closed cervix. It is possible that membrane sweeping, but not cervical massage, may increase the risk of someone’s water breaking before labor, which we call premature rupture of membranes, or PROM, and we have an article all about that at evidencebasedbirth.com/prom.

In one randomized trial, the risk of having your water break was 9% in the membrane sweep group among people who actually had membrane sweeping and not cervical massage versus 0% in the no treatment group. Finally, when we look at when is the best time to have membrane sweeping if you’re going to have membrane sweeping, the Cochrane reviewers state that there is currently not enough evidence to determine the best time at the end of pregnancy to have a membrane sweep or if having more than one sweep would be beneficial. However, I do hear reports of pregnant people being coerced into having membrane sweeps as early as 36 weeks of pregnancy, which doesn’t make sense because you’re not even considered to reach early-term pregnancy until 37 weeks, and full-term pregnancy would be 39 weeks.

Since membrane sweeping is a method of trying to induce labor, it does not make sense to me why providers would want people to go into labor pre-term or early-term when there’s no medical reason to do so. What about satisfaction? Sadly, only three of the 44 studies in the Cochrane review looked at maternal satisfaction with membrane sweeping. In those three randomized trials that looked at satisfaction, there were 675 pregnant people in those studies. The majority of participants reported a positive experience with membrane sweeping. The Cochrane reviewers only talked about one study that looked at pain, and that study, they said that 31% of participants said it was not painful, 51% said it was somewhat painful, and 17% said it was painful or very painful.

They did note that 88% of people who reported pain said they would still choose membrane sweeping again in the next pregnancy. However, very few studies have included maternal satisfaction or pain as an outcome. So more data are needed before it is possible to draw conclusions about pregnant people’s views on this procedure. I have corresponded with many people around the world who had membrane sweeping done without their permission or consent and they usually describe it as a particularly painful vaginal exam. It may be that choice plays a role in the matter and that people who choose with informed consent to have membrane sweeping may have less pain than those who have it done forcibly upon them. However, we have zero research on the subject of forced or non-consented membrane sweeping.

In fact, despite the fact that I hear regularly from women all over the world, including the United States, who’ve had membrane sweeping without consent or even against their wishes or have been pressured into it with coercion techniques, there has never been a study published that I know of on the topic of unconsented membrane sweeping. In fact, it is so common for me to hear of unconsented membrane sweeping that we actually teach about it in our Evidence Based Birth® Childbirth Class. We talk about how if you’re going to have a cervical check or a vaginal exam towards the end of pregnancy that you should have an explicit conversation with your provider and tell them that they may not perform membrane sweeping without your permission.

Another strategy that some people who do not want to have membrane sweeping use to avoid membrane sweeping is to simply decline all vaginal exams towards the end of pregnancy. The problem is, is that some providers consider membrane sweeping to be a routine part of the vaginal exam and they don’t see the need to ask for permission to do that extra step at the end of the vaginal exam. But in fact, membrane sweeping is a medical procedure that requires informed consent. So what are the advantages of having membrane sweeping? First, research shows that membrane sweeping may improve your chances of having spontaneous labor and reduce your risk of having a formal medical induction in the hospital later on. It’s a relatively simple and low cost procedure.

It can be done outpatient in a clinic setting or even at a home visit if you have a home birth midwife. It can be used independently or combined with other methods such as natural induction methods or medical induction methods. And it can be repeated multiple times, although we don’t have evidence yet that this provides benefits to do it repeatedly. What are the disadvantages of membrane sweeping? Sometimes, it’s done routinely during a vaginal exam without an informed consent discussion. People have reported experiencing pain or discomfort with the procedure. You may also experience bleeding after the procedure. Membrane sweeping, but not cervical massage, may increase the risk of your water breaking before labor.

People also report that sometimes membrane sweeping triggers irregular contractions that could interfere with your ability to rest or sleep leading up to actual labor. Also, membrane sweeping has not been studied well among people with positive group B strep status, although so far there’s not yet evidence of harm. I also wanted to mention the practice guidelines on membrane sweeping. Guidelines from the National Institute for Health and Care Excellence (NICE) in the United Kingdom, the Society of Obstetricians and Gynaecologists of Canada, and the World Health Organization all state that pregnant people should be offered the option of membrane sweeping at or near term. Specifically, or NICE guidelines from the United Kingdom recommend offering a vaginal exam for membrane sweeping to first-time parents at term and to experienced parents at 41 weeks of pregnancy.

If labor does not start on its own, they say that additional membrane sweeping may be offered. The bottom line is that membrane sweeping is technically a form of induction, albeit not an incredibly effective one, and it does require an informed consent discussion because there are both advantages and disadvantages. Membrane sweeping may lower your risk of needing a formal induction in the hospital. However, its advantages need to be weighed against the disadvantages of primarily pain or discomfort or the accidental rupture of membranes. Membrane sweeping should never be done without the explicit permission of the birthing person. To do this procedure without permission would be a violation of your human rights.

I hope you found this episode helpful. It will be replacing Evidence Based Birth® podcast episode number five. This was actually the fifth topic we ever covered on the podcast. And it’s been really fun looking at the updated research on all kinds of induction methods leading up to our release of the pocket guide for induction in November. So don’t forget to get on our waitlist for that EBB pocket guide. Just go to ebbirth.com/waitlist. Also, just to let you know, there is a lot going on right now in the United States where I’m located. So my team and I have decided that we are taking a break next week from the podcast. We will be back in two weeks with a really important message and podcast from Shafia Monroe. So see you all in two weeks. Thanks for listening. Bye.

This podcast episode was brought to you by the Evidence Based Birth® Childbirth Class. This is Rebecca speaking. When I walked into the hospital to have my first baby, I had no idea what I was getting myself into. Since then, I’ve met countless parents who felt that they too were unprepared for the birth process and navigating the healthcare system. The next time I had a baby, I learned that in order to have the most empowering birth possible, I needed to learn the evidence on childbirth practices. We are now offering the Evidence Based Birth® Childbirth Class totally online. In your class, you will work with an instructor who will skillfully mentor you and your partner in evidence-based care, comfort measures, and advocacy so that you can both embrace your birth and parenting experiences with courage and confidence.

Get empowered with an interactive online childbirth class you and your partner will love. Visit evidencebasedbirth.com/childbirthclass to find your class now.

Listening to this podcast is an Australian College of Midwives CPD Recognised Activity.

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