How dilated do you need to be to have a sweep?

A sweep, also known as a membrane sweep or stripping of the membranes, is a procedure done late in pregnancy to help encourage the onset of labor. It involves your doctor or midwife inserting a finger into the cervix and rotating it in a circular pattern to separate the amniotic sac from the lower part of the uterus.

For a sweep to be performed, you need to have begun dilating and effacing. Dilation refers to opening or widening of the cervix, while effacement refers to thinning of the cervix. Here’s a look at how dilated you typically need to be to have a sweep:

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What is dilation and effacement?

During pregnancy, the cervix is normally closed and firm. As you near labor and delivery, the cervix begins to ripen in preparation for birth. Signs that the cervix is ripening include:

The cervix starts to soften, known as effacement
The cervix begins to open, called dilation

Effacement is measured as a percentage, while dilation is measured in centimeters (cm):

0% effacement means the cervix is still very thick
100% effacement means the cervix has thinned out completely
0 cm dilation means the cervix is completely closed

10 cm dilation is fully open and ready for delivery

As you get closer to your due date, your doctor or midwife will begin checking your cervix during prenatal exams to track changes in effacement and dilation.

How dilated do you need to be for a sweep?

There is no set dilation requirement to have a membrane sweep done. However, there are some general guidelines that many providers follow:

At least 1 centimeter (cm) dilated
Around 50% effaced

With at least 1 cm dilation and 50% effacement, there is enough cervical opening and thinning for the provider to be able to reach in and separate the amniotic sac from the lower uterus.

Some key points about dilation and sweeps:

The more dilated and effaced you are, the easier it is to do a sweep.
Providers may consider doing a sweep earlier than 1 cm if you are very effaced.

There is no maximum dilation for when you can have a sweep.
Sweeps can be done multiple times, as long as cervical changes are still happening.

Membrane sweeping risks

Membrane sweeping is generally considered safe, but there are some potential risks and concerns to be aware of:

Infection – Sweeping separates membranes from your uterus, which could allow bacteria to be introduced. The risk is still low.
Rupture of membranes – Rough sweeping could accidentally rupture your amniotic sac. This may lead to interventions if labor doesn’t start soon after.
Pain/Discomfort – You may have some cramping, pressure, or change in vaginal discharge after the procedure.

Bleeding – Spotting can sometimes occur after a sweep.
Putting you into labor – This is the goal, but it’s possible to go into labor very soon after.
Not working – Be patient, as sweeps don’t always trigger labor right away.

Talk to your provider about whether the potential benefits of a sweep outweigh any possible risks in your situation.

When are membrane sweeps typically done?

The timing of when sweeps are performed can vary based on your provider’s practice and your individual circumstances. But here are some general guidelines on when they may be done:

Weeks Gestation	Typical Timing
38-40 weeks	Often offered starting at 38 weeks if you are dilated to 1cm and 50% effaced.
40-42 weeks	Typically recommended if you go past your due date and wish to avoid formal induction.
41+ weeks	Many providers will do serial sweeps (such as weekly) after 41 weeks to encourage labor.

Earlier than 38 weeks, a sweep is not typically recommended unless there are special medical circumstances.

How long after a sweep does labor start?

There is no set timeline for when labor will start after having a membrane sweeping done. Some general statistics on onset of labor after sweeping:

Within 24 hours – Around 20% of women
Within 48 hours – Over 50% of women

Within 1 week – Up to 80% of women

However, there are still around 20-30% of women who do not go into labor within a week after sweeping.

Some factors that may influence how quickly sweeping works to induce labor:

How dilated and effaced your cervix already is
If this your first pregnancy or you’ve had children before
The number of membrane sweeps done

Use of other natural induction techniques, like nipple stimulation

Give it 24-48 hours after a sweep before you try natural induction methods to enhance the effect. If you don’t go into labor within 1 week, your provider will discuss your options.

Steps of having a membrane sweep

If you decide to have a membrane sweeping done, here is a basic idea of what the process will be like:

Your provider will have you lie back on the exam table, as with a regular prenatal checkup.
They will insert two fingers through the vaginal opening and into the cervical canal.
The fingers will rotate in a circular motion to separate the amniotic sac from the lower uterus/cervix.

This typically only takes about 30 seconds to perform.
You may feel some menstrual-like cramping during and after the sweep.
There is a chance you could have some spotting or your water breaking after.

Once finished, you are free to carry on your day as normal!

What to expect after a sweep

Here’s what to expect in the hours and days following having a membrane sweeping procedure:

Cramping/Contractions – This is a positive sign it is stimulating labor!

Spotting – Some light bleeding or blood-tinged discharge may occur.
Water breaking – Membrane rupture can happen right away or within 24-48 hours.
Diarrhea – Prostaglandins released can cause this temporary symptom.

Baby moving lower – You may feel increased pelvic pressure as the baby drops down.
No signs of labor – It can take up to a week to go into labor after a sweep.

In most cases, women are able to resume their normal daily activities after having a sweep. But take it easy if you start having stronger contractions or other symptoms.

Let your provider know if you have heavy bleeding, think your water broke, or signs of infection after the procedure.

Maximizing your chances from a sweep

To help make a membrane sweeping as effective as possible in starting labor, here are some tips:

Stay well hydrated by drinking extra water

Go for walks to keep moving
Have sex or nipple stimulation to increase oxytocin
Use your birthing ball to rock your hips

Consume dates, raspberry leaf tea, or other natural induction foods
Get acupuncture or acupressure if available
Get plenty of rest before labor begins

If you don’t go into labor within 24 hours, you can try repeating some of these techniques. Stay in touch with your provider so they know if labor starts or if a follow-up sweep is needed.

Repeat sweeps

If your first membrane sweeping does not trigger labor, having additional sweeps done is common. Here’s what you need to know:

Repeats are typically done at 1-week intervals if you remain pregnant.

You need to have continuing cervical change for another sweep.
More than 2-3 sweeps is rarely found to be beneficial.
If labor doesn’t start after 2-3 sweeps, formal induction would be the next step.

The same dilation guidelines apply for follow-up sweeps – usually at least 1 cm dilated and 50% effaced.

Serial sweeps around 41 weeks and beyond may help avoid having to be induced if the pregnancy continues past your due date.

Sweep instead of formal induction

Having your labor induced can take a while and make contractions more intense. So many women hoping to have a natural childbirth want to avoid being induced if possible.

If you go past your estimated due date, having a membrane sweep or series of sweeps is an option to try before formal medical induction methods like Pitocin or breaking your water.

Research has found membrane sweeping around term decreases the need for formal inductions, with numbers needed to treat of:

8 women treated to prevent 1 formal induction at 38-40 weeks

4 women treated to prevent 1 formal induction at 41+ weeks

So while sweeps do not always work, they reduce the chances you will need to be induced if pregnancy continues past your due date.

Risks of going past your due date

Due dates are just estimates, but there are some risks associated with allowing pregnancy to continue too far past your estimated due date. These include:

Placenta aging – The placenta works best by 40 weeks and may not function as well after.
Larger babies – Babies tend to grow bigger the longer they remain in utero.
Stillbirth – Risk approximately doubles from 39 to 42 weeks.

Meconium issues – Older babies may pass stool in the womb.

Your provider will monitor you and baby closely if you go past 40 weeks. Sweeps and induction may be recommended to lower these risks.

When to avoid sweeping membranes

While generally considered safe, your doctor may recommend not doing a membrane sweep if certain conditions are present, including:

Preterm premature rupture of membranes (PPROM)
Placenta previa or vasa previa
Active vaginal bleeding or infection

Prior history of miscarriage or preterm birth

You should also avoid sweeping if you are GBS positive until you’ve had adequate treatment with antibiotics.

Talk to your provider about your unique circumstances to see if sweeping is appropriate for you.

Cervical checks without sweep

If your doctor or midwife does not feel comfortable doing a sweep, or it is medically not advised, they can still perform cervical checks to monitor effacement and dilation as you near labor.

Cervical exams without sweeping membranes may show:

If induction would be favorable based on dilation/effacement

Early signs of labor starting naturally
No progress, signaling the need for a sweep or induction

Routine cervical checks allow your provider to give guidance about when to try natural induction techniques or come in for formal induction.

Conclusion

Many providers perform membrane sweeping to help stimulate the start of labor once you are full term or past your due date. For a sweep, you typically need to be dilated around 1 cm and 50% effaced.

Sweeps can be done starting around 38 weeks, with multiple repeats if needed. They are more successful the more effaced and dilated your cervix already is.

It can take anywhere from hours to a week for labor to start after a sweep. Taking a patient approach while using natural induction methods can help boost your chances.

Membrane sweeping is an option for encouraging the onset of labor and avoiding formal medical induction when possible. Discuss the risks and benefits with your provider to see if it is appropriate for your situation.