What Is A Membrane Sweep?

You’ve been to a pregnancy appointment with your doctor or midwife.

Your healthcare professional has mentioned a membrane sweep, or a ‘stretch and sweep’ of your cervix.

You might be near your due date, you’re having irregular contractions, or perhaps there’s a medical reason for birthing baby sooner than expected.

You could be nearly 42 weeks and discussing labor induction.

A membrane sweep sounds like a less invasive option than a medical induction. But what is it?

Read on. I’ll be the midwife at your ‘cervix’ and I’ll debunk the mystery of membrane sweeps.

What is a membrane sweep?

A membrane sweep (or stretch and sweep) is a procedure where healthcare professionals feel for the amniotic sac, or membrane, that surrounds the baby, where it meets the cervix.

And then they ‘sweep’ it off the cervix, and stretch the cervix open if they can.

Sounds simple, right?

Membrane sweeping doesn’t come without risk, however, even though it seems like a natural way to induce labor.

It’s still an intervention that can lead to a cascade of intervention in your pregnancy and birth.

Understanding how your body works during pregnancy and birth will help you in your decision-making and birth preferences.

It also helps if you write a birth plan and discuss it with your midwife or doctor.

How is a membrane sweep done?

A membrane sweep is a procedure that involves a vaginal exam.

You should always be asked to give your consent for this, and any other procedure by any health professional.

You lie on your back, usually on an exam table, with your knees bent and legs apart.

Your doctor inserts gloved fingers into your vagina, to reach the opening of the cervix (the neck of the womb or uterus).

Sometimes the cervix can be difficult to reach, and you might feel some discomfort.

Once you’re comfortable, the doctor will assess the effacement (thinning) and dilation (opening) of your cervix. This is to find out how ‘ready’ your cervix is for birth.

The membranes are then ‘swept’ off the cervix. The cervix may also be stretched.

Once completed, your midwife or doctor should discuss with you what they felt during their examination, and what the next step in the induction process will be.

How does a membrane sweep work?

As you approach your due date, your body starts to produce more hormones and hormone receptors.

Prostaglandins and oxytocin are the two main hormones in labor.

The prostaglandins are found in your blood system and in amniotic fluid. The amount of prostaglandin is increased during pregnancy and peaks around your due date. It works with your uterus to ripen and open your cervix

This can stimulate your body to produce more prostaglandins and encourage contractions to start.

The hormone oxytocin causes contractions and also increases production of prostaglandins. These work in harmony to increase the contractions even further.

Read more about those amazing hormones in Hormones In Labor & Birth – How Your Body Helps You.

How far dilated do I have to be for a membrane sweep?

Before pregnancy, your cervix is tightly closed and long, like a cylinder.

In late pregnancy, the cervix softens, shortens, and opens. This happens in preparation for birth.

During the vaginal examination, your health provider will assess the effacement and dilation of your cervix and calculate a Bishops Score. This is done to determine how successful induction is likely to be at this point.

For a membrane sweep to be completed, your cervix needs to be slightly open, enough to place a fingertip inside your cervix. Normally this is 1-2cm dilated.

Why would I have a membrane stripping or stretch of my cervix?

A membrane sweep is commonly offered as an initial induction method if you’re past your due date or you are nearly at 42 weeks.

Occasionally this might be offered earlier if there is a non-urgent medical reason for your baby to be born.

The reasons might be:

• You have been diagnosed with gestational diabetes
• You have pregnancy-induced hypertension (high blood pressure during pregnancy)
• You have pre-eclampsia
• There has been a change of pattern in baby’s movements or growth, or less fluid around the baby.

Should I have membrane sweeping after my due date?

The risks associated with induction for pregnancies at or beyond term are documented in the Australian Government Pregnancy Care Guidelines and by a recently updated Cochrane Review.

The Cochrane Review included 34 randomized controlled trials and the health outcomes of over 21,000 women.

The summary of this review was:

• After the due date, the risks of stillbirth or neonatal death increase (although the number is still very small)
• There are many health risks associated with induction
• Research is still unclear whether early induction reduces risks to you and your baby
• Induction after ‘term’ results in fewer c-sections and fewer neonatal intensive care admissions.

A membrane stripping could avoid other methods of induction, and is best discussed with your care provider.

Read this BellyBelly article on how you could have a positive induction of labor experience.

Should I have a membrane sweep before 40 weeks?

A pregnancy is considered ‘term’ after 37 weeks and up to 42 weeks.

Once you are past your due date your body is getting ready to birth. Those hormone receptors are being primed, waiting for your body and baby to decide on baby’s birthday.

You might even consider natural induction methods if you are around 41 weeks.

If you have a membrane sweeping prior to this, your body might not respond, and further intervention might be needed.

You could also have side effects that call for medical attention, such as an irritable uterus or an infection from ruptured membranes.

It isn’t recommended to have a sweep before your ‘due date’ unless there is a valid medical reason.

Your health care provider needs to discuss any concerns with you so you can give informed consent to the procedure.

What are the risks to my pregnancy or my baby?

You might be worried about the actual risk to you and your baby, or that there will be complications from the stripping of the membranes.

The immediate risks of membrane sweeps are:

1. Vaginal bleeding or spotting from broken blood vessels
2. Infection
3. Amniotic sac rupture or ‘waters breaking’
4. Ongoing cramping
5. Discomfort during the membrane stripping.

If you experience any of these signs, please contact your healthcare provider immediately.

The risk of the actual sweep causing harm to your baby is very low.

The sweep is an intervention, however, and there’s no guarantee it will bring labor on.

How do I know a membrane sweep has worked?

A membrane sweep is often deemed successful by your doctor or midwife, when it helps ‘kick off’ labor.

You could have tightening’s that eventually turn into contractions, further dilating your cervix.

A membrane sweep can be offered every second day. This enables your body to utilize any of the tightening’s or cramps the sweep causes.

Want to know more?

Here is a BellyBelly article with 5 important facts about membrane sweeping.

Discuss it with your doctor or midwife, as you approach your birth.

The choice to have a membrane sweep or not, however, is yours alone.