Many women, whether by medical necessity or personal preference, will undergo induction of labor during their pregnancies. There are many methods available, both natural and medical. Some of these methods are research proven, others are old wive’s tales that have been shown to be ineffective, or even harmful. This series will look at research articles regarding different methods commonly used, and their effectiveness at inducing labor. Part 1 of this series will discuss research on Membrane Stripping.
Disclaimer: None of these methods should be used unless recommended by your provider, not even the natural methods. “Natural” does not automatically mean risk free. Some common recommendations are evidence based; others are passed on as old wive’s tales and are ineffective or possibly harmful. Normal, low risk pregnancies should not be induced prior to 39 weeks, and ideally not before 41 weeks, without a medical indication. Healthy babies will come when they are ready. Taking the baby too soon can result in breathing and feeding difficulties, as well as increase the risk of c-section. Mom being uncomfortable, having difficulty sleeping, multiple rounds of false labor, or excitement for the baby to come are NOT reasons to induce. That being said, there are times when induction is appropriate, and this decision should be made with your provider.
Zamzami, T. and Senani, N. (2014). The efficacy of membrane sweeping at term and effect on duration of pregnancy: A randomized controlled trial. Journal of Clinical Gynecology and Obstetrics. 3(1).
Membrane stripping is also known as a “membrane sweep”, or a “stretch and sweep”. The provider will perform a vaginal exam and stretch the cervix, followed by a sweeping motion with their fingers to try to separate the amniotic sac from lower uterine segment. This is thought to release a type of hormones known as prostaglandins that help the body prepare for labor, but the exact mechanism is not well understood.
This study by Zamami and Senani was a randomized controlled trial, considered the “gold standard” of research trials. Women who were considered candidates for the membrane stripping were singleton pregnancies (no twins, etc), cephalic presentation (head down), had no more than 1 prior c-section, and were anticipated to have vaginal delivery. Women were excluded if they had medical indications for induction, needed a cesarean section (such as for placenta previa, where the placenta grows over the opening of the cervix), or had an active herpes infection. Women in the treatment group had weekly membrane stripping starting at 38 weeks until delivery. Women in the control group had no intervention. At 41 weeks, all women who were still pregnant, regardless of treatment or control group, were admitted for induction of labor.
The results showed that 90% of women in the treatment group went into labor by 41 weeks, compared with only 75% in the control group. Of those that delivered in the treatment group, 81% delivered between 39-40 weeks after only 1 membrane sweep. There were no statistical differences between rates of c-sections, or of maternal or fetal complications. Rates of fetal distress, APGAR scores, and NICU admissions were similar between groups. There was a statistically significant increase of macrosomia and meconium in the control group, likely due to the increased length of the pregnancies. Those from the treatment group who had not gone into labor by 41 weeks had a higher bishop score and a more favorable cervix than those in the control group when admitted for their induction.
Possible harms of membrane stripping included maternal pain during the procedure, and spotting after the procedure.
The authors conclude that weekly membrane stripping is a safe, low intervention method to decrease the likelihood of pregnancy progressing beyond 41 weeks. Those that do progress past 41 weeks have a more favorable cervix following the intervention.
Discussion: In this study, membrane stripping was performed weekly starting at 38 weeks. The results were positive, and it was found to be effective at shortening the length of pregnancy. While this study did not find a statistically significant increase in premature rupture of membranes (PROM) following the intervention (rupturing of the water before labor has started), there was a slightly higher number of PROM in the intervention group (4 vs 2). PROM is often considered a risk factor of membrane stripping, even if in this case it was not proven by the research and is a theoretical risk. Membrane stripping is an optional intervention, and I do not personally believe that it should be done at all prior to 39 weeks. If there were to be PROM prior to 39 weeks because of the procedure, other risks are increased, including infection, or potential delivery before the baby was ready. Before 39 weeks, the potential harms outweigh the benefits, in my opinion. After 39 weeks, this study found membrane stripping to be safe for mother and baby, and it is the mother’s preference whether she wishes to undergo the procedure, or to let her body progress to labor on its own, without intervention.
Induction Methods Part 2 will feature castor oil. If you have a particular method that you would like featured in the blog, or have any questions, let me know!
Please see the medical disclaimer page. This post is not intended as individual medical advice, and all decisions should be made with your healthcare provider.