Membrane stripping, or membrane sweeping, is a method used to promote earlier onset of labor and reduce the risk of post-term pregnancy. Stripping membranes is a simple, easy, and safe method that can be done in a doctor's or midwife's office.
Induction of Labor by Membrane Stripping
According to Dr. Philip DiSaia's book, Women's Health Review: A Clinical Update in Obstetrics-gynecology (page 124), membrane stripping is a common obstetrics procedure. Your doctor or midwife might suggest to strip membranes to encourage spontaneous onset of labor and reduce your need for other methods of induction of labor. Membrane stripping may also done at the start of other methods, such as the use of oxytocin or prostaglandins, to speed up your labor.
How the Procedure Is Performed
Your doctor or midwife inserts a gloved finger through the mouth (os) of the cervix during a pelvic exam. He sweeps it in a gentle motion between lower part of the uterus and the bag of waters. This easily separates or strips the intact fetal membranes from the wall of the uterus. One stripping procedure can induce labor, or your doctor might repeat it in a week or less depending on your circumstances.
What Happens When Membranes Are Stripped
According to the DiSaia reference, stripping your membranes is thought to release prostaglandins and perhaps other substances from the uterine lining and the cervix. As a result, the cervix softens, effaces (ripens), dilates, and labor starts. Labor will start sooner if the cervix is already ripe before membrane stripping.
When Is Membrane Stripping Suggested?
Why strip the membrane to induce labor? Membrane stripping might be recommended in the following situations:
- You are past 39 to 40 weeks pregnant and your cervix is still firm, long, and closed
- You are past 41 weeks or approaching 42 of pregnancy
- At the start of planned, elective induction of labor
- If you have a medical condition such as preeclampsia, diabetes, or high blood pressure, or there are signs of poor fetal well-being, and earlier labor and delivery is better for you and your baby
Membrane stripping is often performed at 39 weeks and beyond, however, stripping membranes at 38 weeks would depend on your individual pregnancy and your practitioner's rrecommendations. It is not typically performed at less than 38 weeks.
Membrane stripping is effective in initiating onset of labor, according to a 2005 Cochrane Library Database Systematic Reviews analysis of several clinical studies. One study published in 2014 in the Journal of Clinical Gynecology and Obstetrics found the following in comparing membrane stripping (study women) starting to no stripping (control group of women), starting at 38 weeks:
- Successful initiation of labor: 90% of the membrane-stripped study women went into active labor compared to 75% of the no-strip controls
- Less need for formal induction of labor by other methods: 10% of the study group compared to 25% of the control group needed other methods of labor induction.
- Fewer women still pregnant at 41 weeks: 10% of the study women versus 25% of the controls were still pregnant at 41 weeks.
- Earlier labor and delivery: The majority of the women in the study group delivered a week earlier than those in the control, no-strip group
Most of the women in the study group only needed one sweep to initiate labor and a small percent needed two sweeps, which were a week apart.
Benefits and Pregnancy Outcomes
According to the above cited 2005 Cochrane Library Database analysis, compared to no stripping, scraping the membrane to induce labor has the following benefits:
- Reduces the time to onset of labor
- Increases the chance of onset of labor within 48 hours after the procedure
- Reduces the rate of prolonged pregnancy beyond 41 and 42 weeks, thus reducing the rate of post-term pregnancies
- Does not increase the chance of a cesarean section
- Is not associated with increased risk for maternal or newborn infections, or other poor pregnancy, maternal, or newborn outcomes
There was not enough data from the studies to by which to compare outcomes of membrane stripping to use of prostaglandins or oxytocin to induce labor.
Membrane Stripping and Planned Labor Induction
A study published in 2015 in the Obstetrics and Gynecology is one source of evidence that membrane stripping is also beneficial when done at the start of formal, planned induction of labor with prostaglandins or other methods.
According to the study, compared with the women who had no membrane stripping, those with membrane stripping at the start of labor induction with a prostaglandin or active rupture of membranes by the clinician had:
- A higher chance of having a vaginal delivery than a cesarean section
- Shorter interval from induction of labor to delivery
- Less need for oxytocin augmentation of labor
- Better satisfaction with the labor and delivery process
Risks and Cons
The 2005 Cochrane Library Database analysis of studies found that membrane stripping is associated with:
- Discomfort during the procedure
- Irregular uterine cramps after the procedure
- Bleeding from the procedure which is usually light if you have no risk factors
There is a small potential risk for unintentional rupture of membranes before labor starts.
Stripping the membranes is contraindicated in these situations:
- Signs of active vaginal infection that may ascend into the uterus
- Placenta partially or completely covers the cervix which increases the risk for hemorrhage
- Already ruptured membranes, increasing the chance for intrauterine infection
- You or your baby are at risk if you have a vaginal delivery
Ask Your Doctor
How effective is stripping membranes to induce labor? Membrane stripping is easy, safe, and effective for inducing earlier onset of spontaneous labor. Ask your doctor or midwife if you might benefit from membrane stripping if you are past your due date and you have no signs of cervical ripening or labor.