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Induction of labour (IOL)

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This leaflet aims to give you information about induction of labour (IOL), the main reasons for induction, methods by which labour can be induced and to help you understand your choices so that you can be involved in decision making about you and your baby. It includes information about:

  • Why induction of labour may be offered.
  • How we induce labour.
  • What to expect if being induced.
  • What to expect if not being induced.

How your body changes before and during labour

During the pregnancy, your baby is surrounded by a fluid filled membrane, which offers protection whilst he or she is developing in the uterus (womb). The fluid inside the membrane is called amniotic fluid. In preparation for labour the cervix (neck of the womb) softens and shortens. This is sometimes referred to as ‘ripening of the cervix’. Before, or during labour, the membranes rupture (break) releasing the fluid. This is often referred to as ‘your waters breaking’. During labour, the cervix dilates (widens) and the uterus contracts to push your baby out.

The exact mechanism of the start of labour is uncertain but is thought to involve a complex interaction of factors between mother and baby.

In most pregnancies labour starts naturally between 37 and 42 weeks; this is called ‘spontaneous’ labour. However, sometimes pregnancy is prolonged, or the pregnancy is not completely straight forward and induction of labour may be offered.

Membrane Sweep

Membrane sweeping involves you having a vaginal examination and your midwife or an obstetrician placing a finger inside your cervix and, by making a circular movement, gently sweeping the membranes away from the cervix. This procedure can be done either in your own home or in hospital.

This is usually offered when you are 40 - 41 weeks pregnant and it aims to stimulate the natural production of prostaglandins which might speed up the opening of the cervix and in time trigger active labour. You may find the internal examination uncomfortable, and you may experience some bleeding similar to a ‘show’ following the procedure. This is because the internal examination involves stretching your cervix. This is normal and will not cause any harm to your baby. There is no evidence to suggest that labour triggered by this method is any more painful than a labour that starts naturally.

What is IOL?

Induction of labour is the process used to encourage labour to start artificially.

When is IOL recommended?

There are two main reasons why induction of labour is offered:

  • When you have progressed 10 - 14 days past your estimated due date. The aim is to commence the induction process by 42 weeks. If your pregnancy lasts longer than 42 weeks, your baby’s health could be at greater risk because your placenta may not work as well.
  • If the obstetrician looking after you feels that either you or your baby’s health would benefit from earlier delivery. Common worries are diabetes in pregnancy, high blood pressure, concerns for your baby’s growth or problems that have been identified on your baby’s scans.

How is labour induced (started)?

There are three methods of inducing labour; you may have one or a combination of the following depending on your individual circumstances:


Prostaglandins are hormone-like substances that help to induce labour by encouraging the cervix to ripen, soften and shorten. Prostaglandins are inserted into the vagina, either in a tablet form called Prostin®, or as a pessary (medicated vaginal suppository) called Propess®.


This is a tablet form of prostaglandin and is inserted high into the vagina behind the cervix. One or more doses of Prostin® may be required depending on how ‘ready for labour’ the cervix feels during the vaginal examinations and according to your sensitivity to the prostaglandin. A repeat dose can be given after a six-hour interval but no more than two doses are usually given in any 24 hour period. This is most likely to be used if you have had babies before.


This prostaglandin comes in the form of a pessary which is also is inserted vaginally and sits high in the vagina behind the cervix. It is soft and looks like a small tampon and has a string attached to allow for removal. Once the Propess® is inserted it will swell to keep it in place. The Propess® pessary usually remains in place for a maximum of 24 hours. However, it can be removed earlier if there are signs that labour has started.This is most likely to be used if you are having your first baby.

After a period of initial monitoring, you can walk around, shower, eat and drink normally. If the string from the Propess® moves to the outside of your vagina you must be careful not to pull or drag on it, as this may cause it to come out. Please take special care when:

  • wiping yourself after going to the toilet
  • washing yourself
  • getting on and off the bed

In the unlikely event that the pessary should come out, please inform your midwife as soon as possible. If it has come out because your cervix is opening and you are in labour then the pessary will not be re-inserted, however if you are not in labour then the pessary will need to be reinserted during a vaginal examination.

Occasionally prostaglandins can make your womb contract too much and this could affect the pattern of your baby’s heartbeat. Therefore, before and after prostaglandins are given, your baby’s heartbeat will be monitored using a cardiotocograph (CTG) machine.

Breaking the waters - Artificial rupture of the membranes (ARM)

Artificial rupture of membranes may be performed when the cervix has ripened and opened. This is performed by a midwife or an obstetrician on Delivery Unit. During a vaginal examination a slim hook is introduced, and a small hole is made in the membranes/sac around the baby to release the amniotic fluid. Breaking the waters releases natural prostaglandins and encourages the baby’s head to make close contact with the cervix; this further stimulates the release of natural prostaglandins. The stimulation effects may be enough to encourage contractions to start, particularly if you are having your second or subsequent baby.

After your waters have been broken and your baby´s heart rate monitored for a period of time, you will be encouraged to mobilise for a few hours in order to help labour to start. If labour does not start an oxytocin drip will be offered to stimulate contractions; this is often necessary for women having their first baby.

Oxytocin drip (Syntocinon®)

If your contractions have not started or they are not sufficient to open the cervix despite breaking your waters, a drip in your arm containing Syntocinon® will be offered. Syntocinon® is an artificial form of the hormone oxytocin which starts contractions. When the Syntocinon® drip is started, contractions do come on more suddenly than they might do if you went into labour spontaneously, particularly if you have not been prepared by the early/pre-labour contractions. The contractions are not necessarily more painful, just that they started more quickly. The drip is started slowly and increased gradually until your contractions become regular. The frequency, strength and length of contractions, as well as your baby's heartbeat, will all need to be monitored while you receive Syntocinon®.

Arrangements for induction

Most inductions are commenced on the antenatal ward (Sara ward), however induction of labour for some women needs to be commenced on the delivery unit. Speak to your midwife or obstetrician if you have any questions about the area where you are going to be induced. You will be asked to call Sara ward or the delivery unit, depending on your clinical circumstances, at 09:30 on the planned day of your induction to find out what time to come in.

Sara ward direct dial: 01223 217671

There is no time restriction for one birthing partner to stay with you on Sara ward during the whole process of induction. The resting facilities for partners wishing to stay overnight are comfortable chairs next to your hospital bed.

If you wish to have two birth partners, your second partner may attend the ward between 17.00 and 19.30 during visiting hours (maximum of 2 visitors).

Delivery Unit direct dial: 01223 217648

If you wish to have two birth partners, both can be present on the Delivery Unit, but when you return to the postnatal ward after the birth, again only one partner may stay with you.

If your pregnancy is considered low risk and you are suitable to have an Outpatient Induction of Labour, you will be offered to attend Clinic 23 at 08:00 am in the morning for your induction to be commenced. If everything remains normal after the induction is commenced, you will be able to go back home. Your midwife will speak to you about this option.

Place of birth

As IOL usually means you need to have drugs (prostaglandins and/or Syntocinon®) it is important that you and your baby can be monitored during the induction and labour process, therefore you are advised to deliver your baby in hospital.

In the absence of any risk factors, and if you have had a previous vaginal birth before, you will be offered to go to the Rosie birth centre if you go into labour following prostaglandin administration only. If there are risk factors, you need to have your waters broken or you need to have the oxytocin drip, you will be transferred to the delivery unit.

How long will it take?

Every woman is different and starting labour can take different periods of time. In some cases, it can take a couple of days for labour to establish. The average length of stay on the Sara ward before going to Delivery Unit is between 24 - 72 hours.

Due to the nature of maternity care, there are occasions when your induction of labour must be delayed or postponed, or there may be some delay in transferring you to the Delivery Unit. This is because it is not possible to predict the number of women who will go into labour at any one time, or when emergency admissions occur. If this happens, we will keep you informed as much as possible and try to commence or continue with your induction as soon as we safely can. Occasionally we may offer monitoring of your baby while you are waiting to be admitted for induction.

We therefore advise that you prepare and make childcare arrangements if relevant, not just for the day of your induction but for several days afterwards.

Staying mobile and comfort measures

Women who can remain as mobile and upright as possible and to adopt optimal positions for labour, tend to cope better with the pain and have quicker labours than those who do not. Sometimes during IOL doing these things can feel awkward especially when you are being monitored and/or have a drip. Your midwife will encourage and help you remain mobile and try good positions. You should feel free to ask for help if you need it.

Birthing balls are available on Sara ward and delivery unit. If you wish to use them please ask a member of staff for one to borrow, they are a very helpful way of keeping upright and adopting comfortable positions during the induction and early labour process.

As you may be admitted for a couple of days before you go into labour it may be beneficial to bring in any small comforts from home that my help i.e., your own pillow. However, space and storage on the wards is limited, therefore we advise that you only bring the essentials whilst staying with us. If you are on any regular medication or are undertaking blood sugar monitoring, please bring these with you when you come for your induction.

There are showers on the wards that you are welcome to use, and simple pain relief drugs are available if required. If you are thinking of using a TENS (transcutaneous electrical nerve stimulation) machine for pain relief we recommend you bring in your own machine from home, however TENS machines can be ordered on your request.

Eating and drinking

Throughout your stay on Sara ward, you will be encouraged to eat and drink as normal. It may be beneficial for you to bring in some snacks from home, which may be stored in the ward fridge if required. Isotonic or sports drinks may be more beneficial than water and are a good way of boosting energy levels especially during the early stages of labour and beyond. You may bring these with you if you wish.

Unsuccessful induction of labour

Induction aims to tip the balance in favour of labour starting, but occasionally this does not work, and we say that the induction has been unsuccessful or “failed”. In these rare cases you may be offered a caesarean section to deliver your baby.

What to expect if you choose not to have induction of labour for prolonged pregnancy

If you choose not to be induced at 10 - 14 days past your estimated due date and the pregnancy is prolonged, after this time you will be offered a consultant appointment to discuss ‘expectant’ management which may include:

  • An ultrasound scan to check your baby’s growth and amount of fluid (waters) around the baby.
  • A check of your baby’s heartbeat using a CTG machine.

These are used to assess your baby’s health status at that particular time; however, these checks cannot always predict how your placenta will continue to function or how your baby will cope once labour begins.

Further information

If you have any queries at any time, please discuss these with your doctor or midwife.

More information is also available from:

Privacy & dignity

Same sex bays and bathrooms are offered in all wards except critical care and theatre recovery areas where the use of high-tech equipment and/or specialist one to one care is required.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151