What happens during induction of labour?

Norgine Pharmaceuticals provided a Grant to support the development of this material. Norgine had no editorial control or scientific input into this material. 

On this page:

  • Induction and augmentation of labour
  • Membrane sweep (stretch and sweep)
  • Checking your cervix
  • Inducing labour when your cervix is not ready (not ripe)
  • Inducing labour when your cervix is ready (ripe)
  • How long will an induction take?
  • Is it better to be induced in the morning or the evening?
  • What should I do the night before an induction?
  • Are there any ways I can help labour start myself? 

 

Induction and augmentation of labour  

When your body and your baby go into labour naturally (without any medical intervention), certain things start to happen.

  • Your cervix (the neck of your womb) gets ready to open (dilate) - it gets softer and thinner and moves to sit in front of the baby’s head.
  • You have contractions, to open (dilate) your cervix.
  • Your waters break (before or during contractions or as your baby comes out).
  • You feel the urge to push your baby out.

These changes happen because of different hormones released in your body at different times. Read more about the stages of labour here.

Induction of labour helps some or all these things to happen artificially.  

The way labour is induced depends on what needs to happen inside your body for labour to start and continue. You may need to try more than 1 way before your baby is born.

Augmentation of labour is where your labour has already started without medical help, but doctors use 1 or more of these methods of induction to speed up your contractions or keep them going.  

If you are unsure of any words your midwife or doctor uses, ask them to explain what they mean. You will need to give your permission (consent) for an induction or augmentation of labour. You can only do this if you understand what is being said and what will happen. Find out more about informed consent here. 

Membrane sweep (stretch and sweep)

Your midwife or doctor will usually suggest doing a membrane sweep (sometimes called a ‘stretch and sweep’ or ‘cervical sweep’) as the first part of induction.

Your doctor or midwife will gently insert their gloved finger into the vagina and sweep around the neck of your womb (the cervix). You will need to give permission for your midwife or doctor to do both the internal examination and the membrane sweep. You should not be asked to consent to a membrane sweep while you are having an internal examination, as you need time to think about it first.

A membrane sweep might bring on labour within the next 48 hours, without needing a medical induction. It will not usually be offered before 39 weeks of pregnancy.

You may also be offered a membrane sweep at antenatal appointments after 39 weeks, even if there is no reason for you to have the baby now. There is some evidence to show that a stretch and sweep might help labour to start sooner, but more research is needed to show if it can prevent other medical interventions into labour.

You might find it helpful to read our information on why and when labour is induced and making decisions in pregnancy to help you decide if this is right for you.  

A membrane sweep can be uncomfortable but not painful. If you are in hospital, you can ask for gas and air (Entonox) if you need it.

You may have cramping and light bleeding afterwards.

There is a small risk that your midwife could accidentally break your waters. If your waters break but contractions do not start in the next 24 hours, you may be advised to move on to the next stage of induction. This is because of the increased risk of infection if your waters break before you are in labour. This might be fine if you were planning on a formal induction anyway.  

A membrane sweep will not be offered if you have placenta praevia (where the placenta blocks the opening of your cervix). This is because it may not be possible or safe for you to have a vaginal birth. It also may not be suitable if you have had lots of bleeding during your pregnancy.  

It does not always work. Your body may not be ready to go into labour – for example, you may not have enough of the hormones needed to start your contractions. 

Checking your cervix

If you choose to go ahead with the next stage of induction, your midwife or doctor will ask for your permission to examine you inside your vagina. This is so they can check how ready or ripe (soft and open) your cervix is for giving birth. This will show the best way to induce your labour.

They should make sure you understand all your options. You can read more about discussing your options in our information on talking about induction with your midwife or doctor.

Inducing labour if your cervix is not ready

If your cervix is not ready it needs to be made soft and open, ready for your baby to pass through (sometimes called ripening). This can be done using hormonal or mechanical (physical) methods.

If you choose a physical method, you may want to go home during this part of the induction. You may also be able to go home if you have some types of synthetic hormone.  Speak to your midwife or doctor. They should explain any risks and benefits of being at home and staying in hospital. If you go home, you should contact your midwife, doctor or maternity unit if:

  • your contractions start
  • your contractions do not start within a certain number of hours
  • your waters break
  • you start bleeding
  • your baby is moving less than usual
  • your contractions are too painful, long or frequent
  • you have any problems that may be caused by the treatment
  • the treatment falls out
  • you feel unwell or have a high temperature (fever).

 

Balloon catheter

A balloon catheter is a soft tube with a small balloon at the end. The balloon is put inside your cervix and slowly filled with water to help open your cervix. A double balloon catheter involves using two balloons, one inside the cervix and one in your vagina12. The pressure of the balloon or balloons encourages the body to release its own hormones to help start labour instead of using synthetic hormones.13 

A balloon catheter may be an option if you cannot have – or do not want – prostaglandin medicine. Some hospitals may suggest trying a balloon catheter before trying prostaglandin medication.

You may feel uncomfortable when the balloon catheter is being put in, and while it is inside you.     

If you do not go into labour, the balloon catheter will be taken out after about 12 hours. Your midwife or doctor will talk to you about other options to prepare your cervix and start contractions. 

Osmotic dilator (cervical rods)

You may hear these called cervical ripening rods or Dilapan-S. Thin rods are put inside your cervix for up to 24 hours. They act like sponges, taking in fluid from the surrounding tissue. This can help to soften your cervix and encourage your body to release hormones that help start labour. They are not available in all hospitals. 

You may feel uncomfortable as the rods are put in and have some light bleeding. 

You will usually be offered another internal examination after 12–24 hours, to see if your cervix is ready for labour. 

Similar to a balloon catheter, the rods will be taken out if you do not go into labour. You may be able to have new rods put in for another 12–24 hours18. Your midwife or doctor may then talk to you about other options to ripen your cervix and start contractions.

 

Synthetic (artificial) prostaglandin hormones

Synthetic prostaglandin (also called Dinoprost, Cervidil, Misoprostal or Prostin) works like the body’s natural prostaglandin hormones. It softens and opens the cervix and can help to start contractions.  

You may have prostaglandin in the following ways:

  • pessary – like a tiny, flat tampon that goes in your vagina and releases medicine for up to 24 hours
  • vaginal gel – you may need a second dose after 6 hours
  • vaginal tablet – you may need a second dose after 6–8 hours
  • tablets that you swallow – you may take 1 tablet every 2 hours, or 2 tablets every 4 hours, up to a maximum of 8 tablets.

Here, Shivaunne talks about her experience of having a prostaglandin pessary.

 

Possible side effects of synthetic prostaglandin hormones include:

  • feeling sick (nausea),  
  • being sick (vomiting)  
  • diarrhoea (runny poo)
  • hyperstimulation of the womb

Hyperstimulation of the womb means your womb is contracting too much. This could affect your baby’s heart rate. If this happens, your midwife or doctor will try to slow your contractions by stopping this medicine and, if possible, removing it. They may give you a different medicine to slow your contractions.

If your contractions do not start after having prostaglandin, your midwife or doctor may suggest inducing your labour with an oxytocin hormone drip. They may offer to break your waters if they have not yet broken. 

Around 500 in every 100,000 women and birthing people who use synthetic prostaglandin after having a c-section in the past will have tearing in the wall of their womb. If you have never had surgery on your womb, the risk is less than 1 in every 100,000. This is rare.

If your womb tears, you would need an emergency c-section to deliver your baby safely.

Synthetic prostaglandin may not be suitable for you in the following situations.

  • If you have already had 4 births or have had a very fast labour and birth in the past (precipitous birth). This is because you may be more likely to have very strong, frequent contractions, and prostaglandins could add to this risk.  
  • If you have had womb surgery, including a c-section, in the past. This is because very strong, frequent contractions could tear your womb.  
  • If you have placenta praevia (where the placenta blocks the opening of your cervix), or have had unexplained bleeding during your pregnancy. This is because it may not be possible or safe for you to have a vaginal birth.

If you cannot have synthetic prostaglandin, you may be offered a balloon catheter or an osmotic dilator instead. 

Inducing labour when your cervix is ready

It can take several hours or even days for your cervix to get ready for labour.  

Once your cervix is soft and ready for labour, your contractions may start on their own. If not, your midwife or doctor may offer to break your waters artificially and/or give you an artificial oxytocin (syntocinon) hormone drip.

Breaking your waters  

Your midwife or doctor may offer to do this at the hospital if your cervix is ready for labour, but your waters have not yet broken. It is also called an amniotomy or artificial rupture of membranes (ARM).

They will need to do a vaginal examination to break your waters. They will use a small plastic hook to make a hole in the sac of fluid around your baby. This will let the fluid leak out of your vagina. Once your waters have broken, your baby’s head should press on your cervix. This may help to start your contractions and speed up your labour.

Breaking your waters may be uncomfortable, but it should not hurt. It might not work the first time, so your midwife or doctor may need to do it more than once.  

If your contractions do not start within 2–4 hours, your midwife or doctor will usually recommend an oxytocin hormone drip to help them start. You can choose how long you wait, although you may be encouraged to follow hospital policy.

‘The midwife told me they were going to do an ARM. I thought this meant they were going to put their arm inside me to help the baby come out.’

Leah 

There is some evidence that breaking your waters can speed up induced labour if it is done at the right time. It is not recommended if you have:

  • active herpes or HIV
  • vasa previa (a rare condition affecting between 1 in 1200 and 1 in 5000 pregnancies where some of your baby’s blood vessels from the placenta or umbilical cord cross, unprotected, in front of the birth canal inside the membranes)
  • funic or cord presentation (where the umbilical cord is between your baby’s head and your cervix).

The amniotic sac (your waters) protects your baby from infection. When it is broken, there is a risk of infection, especially if you have a lot of vaginal examinations afterwards. This means that if induction doesn’t work, you may be encouraged to have a caesarean.  

Synthetic (artificial) oxytocin hormone drip

Your body produces oxytocin to start contractions naturally. But this does not always happen in induction of labour.

You will usually be offered synthetic oxytocin (called syntocinon or pitocin) if your cervix is ready and your waters have broken, but your contractions have not started.

If you have had synthetic prostaglandin hormones to help prepare your cervix for labour, you will need to wait 6 hours before starting synthetic oxytocin.

Inducing labour with synthetic oxytocin means you have stronger contractions faster, without the slow build-up of spontaneous early labour. This can affect how your body deals with the pain. You may need more pain relief.  

Oxytocin is released by your brain. The amounts released are affected by hormones that change depending on your baby, your environment, your womb and your emotions. If you or your baby are stressed, the amount released will change.  

Oxytocin affects your brain as well as your uterus, helping with relaxation, bonding and relieving pain. Only a small amount can cross into your baby’s brain. 

After your baby is born, high levels of oxytocin are released. This helps create contractions to birth the placenta and to help with breastfeeding.

Synthetic oxytocin (called syntocinon or pitocin) is released at a constant rate through a drip in your arm. This rate is not changed by anything happening in your body. This means midwives and doctors have to monitor you and your baby closely to make sure you are both coping with contractions.  

Synthetic oxytocin does not affect your brain in the same way as oxytocin. This means you do not have the positive benefits of oxytocin.  

It can cross into the baby’s brain at high levels.  

You will have synthetic oxytocin though a drip into a vein in your arm. Your midwife will use a machine (usually strapped to your bump) to constantly monitor your baby’s heartbeat. This is so they can make sure your womb is not contracting too much (hyperstimulation) and that your baby is coping with induced contractions. If your midwife or doctor is worried that your womb is contracting too much, they will remove your drip.

This means you can only have synthetic oxytocin in hospital. Some hospitals do not have monitoring equipment that can be used in a birth pool. This means you would not be able to have a water birth.

You will also be asked to give permission for regular vaginal examinations. This is so your doctor or midwife can make sure the contractions are opening your cervix.

After your baby is born, you will need an additional dose of synthetic oxytocin in to help you birth the placenta (this is called ‘active management’). This has been shown to reduce the risk of losing too much blood after birth in induced labours.

If you do not go into labour, your midwife or doctor should talk to you about possible next steps. These include:

  • trying to induce your labour again
  • waiting to see if you go into labour naturally, while regularly checking your baby’s health
  • a c-section – this may be encouraged if your waters have broken, because of the increased risk of infection. 

Synthetic oxytocin may not be suitable for you if:

  • you have had womb surgery, such as a c-section, in the past
  • you have placenta praevia (where the placenta blocks the opening of your cervix),
  • you have been advised not to have a vaginal birth for any other reason
  • you do not want regular vaginal examinations

Risks, side effects and complications linked with synthetic oxytocin are:

Syntocinon (a type of synthetic oxytocin) can cause water retention. This could mean your baby has a higher birth weight. You baby will lose this extra fluid through their wee in the first few days after they are born. This can make it seem as if they have lost more weight than they should or are not gaining weight fast enough.

There is not enough research to tell us exactly how high levels of artificial oxytocin might affect your baby. Some studies have suggested it might affect their bonding and breastfeeding behaviour immediately after birth.

How long will induction take?

Once the induction process starts, it can happen quickly or take several days for your baby to be born.  

If your cervix is not yet ready for the birth, this part of the induction could take 2 days or more. If you are on a hospital ward, your partner may not be able to stay with you all the time. Have a look at our information on things to think about when making a decision about induction.

 

Is it better to be induced in the morning or the evening?

There is no good evidence to say whether it is better to be induced in the morning or the evening.  In the past, when drugs had an instant effect on your body, it was thought to be better to be induced in the morning. Now, most drugs used to get your cervix ready are ‘slow release’, which means it is released into the body slowly over 24 hours. This means it may not matter so much when you are given it.

When an induction starts will probably depend on the hospital where you will give birth. If you want to be induced at a particular time or on a certain day, talk to your midwife or doctor to see if this is possible.

My pessary was inserted at about 5am, I began having contractions at around 4pm and around 8 hours later my daughter was born.

Nicole

 

How can I prepare for an induction?

Writing a birth plan for induction of labour can help you think about your options and feel more in control. It can also make sure your birth partner, doctor and midwife know what you want.  

It might help to think about these things.

  • Methods of induction you do and don’t want.
  • Methods of pain relief you want/want available in case.
  • What will happen while you wait for your cervix to ripen – will you stay in hospital or can you go home?
  • Who do you want with you to support you?
  • Do you want to wait after breaking your waters to see if contractions start by themselves before starting synthetic oxytocin? How long do you want to wait?
  • Do you want wireless/waterproof CTG monitoring if possible so you can move around/be in a pool?
  • Would you like to move around and use equipment such as birth balls, mats, bean bags if you need to be in hospital?
  • Do you want to hear your babies heart rate all the time?
  • How do you want people to interact with you while you are in labour?
  • How do you want care providers to ask for your consent. Do you want them to verbally ask each time? What would you prefer them to do if not?
  • How do you want vaginal examinations carried out and what do you want to be told about them. Do you want them very regularly or as little as possible?
  • Do you want to try turning synthetic oxytocin down or off once you have established contractions? Do you want to turn it down towards the end of labour to make more space between contractions?
  • How would you like to push your baby out? What position would you like to be in?
  • What do you want to happen immediately after birth? Do you want to lift baby up to you? Do you want skin to skin?

I had a positive induction.  I had gone 10 days overdue with my second and that really threw me off as my first baby arrived right on time. I had a moment of feeling really upset when I realised that she was probably not going to come on her own. I spent some time going over my hypnobirthing videos again and read some positive induction stories online before going into hospital.

Nicole

 

Are there any ways I can help labour start myself?

In some cultures, it is common to try things like hot baths, enemas, acupuncture, homeopathy, herbal supplements or having sex. None of these have been proven to work. Some people believe that stimulating their nipples or expressing their milk by hand could start their labour. But again, there is no evidence that this can trigger labour.

There is some evidence that castor oil may be effective in helping ripen the cervix and start contractions but there is not enough research to tell us how much is safe to take and when is best to take it.

No-one knows how safe herbal supplements are during pregnancy, so these are not recommended.

It is usually safe to have sex during pregnancy. But you should not have sex if your waters have broken, as it could increase the risk of infection. 

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Review dates
Reviewed: 08 May 2024
Next review: 08 May 2027

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