juno midwives

There are several different methods of induction of labour (IOL), but they are broadly separated into two categories: mechanical methods and medicinal methods. Mechanical methods involve using hands or devices to physically stretch and open the cervix and medicinal methods rely on synthetic hormones to achieve the same goal. This blog will discuss the most common forms of IOL, including those used at our local East Kent NHS trust. Settle in, it’s a long one!

Membrane sweep

A membrane sweep involves a midwife or doctor inserting two gloved & lubricated fingers into the vagina to try and reach the cervix to both manually stretch it with their fingers and to try and separate the bag of waters surrounding the baby from the lower part of the uterus – the aim of this is to stimulate the release of the body’s natural prostaglandins to help start labour.

They are considered a form of IOL by the NICE guidelines, which advise that women be offered membrane sweeps from 39 weeks of pregnancy. Research suggests that sweeps may increase the likelihood of ‘spontaneous’ labour – an oxymoron given that a sweep is considered a form of induction – but what they mean is avoiding further methods of induction, which could be seen as a benefit. It could be argued that a ‘successful’ membrane sweep (i.e. one that starts labour off) could just be down to the baby and the woman or birthing person’s body being ready for labour to begin anyway. If a membrane sweep is ‘unsuccessful’, further sweeps may be offered. It is also worth noting that anecdotally, membrane sweeps are not often presented as a form of induction, but as a means to avoid the hospital-based methods. It is always your choice to have a membrane sweep or not – even if it is presented as something that is routine and hospital policy. 

Potential benefits:

• may start labour off, avoiding the need for further methods of induction
• this may mean there is more choice of place of birth – there is no recommendation for continuous fetal monitoring, or closer observation, in an otherwise uncomplicated pregnancy & labour where a membrane sweep has been done

Potential risks / considerations:

• waters may be accidentally broken (you will then need to make further decisions about how you wish to proceed)
• may experience bleeding, pain or discomfort during and after the procedure
• may cause irregular contractions that aren’t doing much to the cervix, but that can prevent resting in the last few days / weeks of pregnancy
• requires a vaginal examination

Other mechanical methods of IOL

Next we will look at two devices that are used for IOL: Dilapan rods & balloon catheters. These aim to open the cervix enough for the waters to be broken. These methods are recommended in certain situations, eg when babies are suspected to be small or if you have had a previous caesarean section. This is because the mechanical methods of induction involve no synthetic hormones, and therefore there is minimal risk of them causing your uterus to hyperstimulate. Hyperstimulation of the uterus is when there are more than 5 contractions in a 10 minute period for a sustained period of time, this can affect the amount of oxygen the baby gets and cause fetal distress (typically identified by changes to the baby’s heart rate observed on a CTG machine). In the case of hyperstimulation, an injection called terbutaline is given to relax the uterus. More than one dose of terbutaline can be given and if it is effective, the uterus will relax and the baby’s heart rate will improve accordingly. If the terbutaline injection does not appear to be working, an emergency caesarean section will be recommended.

Balloon catheters involve a tube being inserted into the cervix and a balloon is then inflated with sterile water to put pressure on the cervix to dilate (single balloon catheter). Another form is where a second balloon is inflated at the lower end of the cervix too (double balloon catheter).

Dilapan are small rods that are inserted into the cervix, which absorb cervical fluid causing them to swell and stretch the cervix.

Both Dilapan and balloon catheters require lying on a bed, with legs in stirrups (lithotomy position), having a speculum inserted into the vagina and then a doctor or a midwife using instruments to place the devices correctly into the cervix. Some women and birthing people find this procedure very uncomfortable or painful and pain relief (such as gas and air) should be offered for the procedure. The length of time the devices stay in the cervix seems to differ across NHS trusts but may be anything from 12 – 24 hours. After this point, a vaginal examination will be recommended to remove them and assess how open the cervix is and if it is possible to break the waters. Mechanical methods of IOL can be requested over medicinal methods.

Potential benefits:

• very low risk of causing uterine hyperstimulation due to there being no synthetic hormones in use
• some NHS trusts may support outpatient use of mechanical methods of IOL – where you go home and return to hospital when the devices are ready to be removed
• considered to be a safer form of cervical ripening (softening & opening the cervix) for those who have had a previous caesarean
• can be easily removed if wanted

Potential risks / downsides:

• pain, bleeding & discomfort during the procedure
• requires a vaginal examination
• some monitoring will be required in hospital before and after the procedure
• accidentally breaking the waters
• devices not being places correctly (therefore not doing their job!)
• can only be inserted if the cervix is already slightly open, otherwise medicinal methods will be recommended
• often further methods of induction are required to stimulate contractions

Medicinal methods of IOL

Medicinal methods of IOL contain synthetic versions of the body’s natural hormones to ‘ripen’ the cervix (Process and Prostin) or stimulate contractions (syntocinon – the hormone drip).

Propess looks like a small, flat tampon and contains synthetic prostaglandins. It is inserted into the vagina and pushed up to sit behind the cervix, where it will swell slightly and release synthetic prostaglandins over a 24-hour period. An advantage of Propess is that it can be removed if necessary (ie. you have too many contractions) and this is why it is generally offered before Prostin. Some NHS Trusts offer two 24-hour cycles of Propess, locally in East Kent one cycle is offered. 

Prostin – this comes in gel or tablet form and contains synthetic prostaglandins. It is inserted into the vagina with a plastic introducer and generally left for 6 hours. Sometimes more than one dose is needed.

Potential benefits:

• may stimulate labour enough that no further methods of IOL are needed
• Propess can be removed if needed and generally involves less frequent vaginal examinations
• some NHS trusts offer outpatient IOL with Propess, and only for IOLs that are considered ‘low risk’ such as those for ‘post-dates’

Potential risks / downsides:

• may cause hyperstimulation
• regular monitoring in hospital of baby before, during and after the procedure is recommended (the length and frequency varies across NHS trusts)
• Prostin cannot be removed once it has been inserted
• both can cause vaginal discomfort and dryness
• Prostin involves more frequent vaginal examinations
• nausea, vomiting & diarrhoea are common side effects of prostaglandins – the full list of potential side effects can be found here

Breaking the waters

Artificially breaking the waters (another mechanical method of IOL) is not usually the first method of inducing labour, unless your cervix is open enough upon arrival at the hospital. Breaking the waters is the step following Dilapan / balloon catheters and / or Propess / Prostin – that’s if your waters haven’t broken spontaneously. The aim of breaking the waters is to stimulate contractions. The midwife or doctor will do a vaginal examination and use a long plastic hook that has a small, sharpened tip (they look a little like long flattened crochet hooks) to puncture the membrane sac around the baby and release the waters. Generally, 2-4 hours after the waters have been broken a vaginal examination would be offered to assess the cervix – the timing of this may depend on the hospital’s local policy, if you’ve had a baby before, if you’re having any contractions, the activity of the ward and what your preferences are…

Potential benefits:

• may be enough to start contractions / labour without needing further intervention

Potential risks / downsides:

• the protective sac of waters around baby is no longer intact, potentially increasing the risk of infection (especially if there are also frequent vaginal examinations)
• procedure can be difficult, uncomfortable and painful
• may cause sudden intense onset of contractions
• may cause some bleeding
• cord prolapse (very rare!) – this is where a loop of the baby’s cord slips down into the and sometimes out of the vagina and is an obstetric emergency, which usually requires an immediate caesarean unless a vaginal birth is imminent
• choice of place of birth likely to be limited

A note on vaginal examinations

Membrane sweeps, Dilapan, balloon catheters, Propess, Prostin and breaking the waters all require vaginal examinations. For a vaginal examination, you will need to be lying pretty flat on your back on the hospital bed, underwear removed, knees drawn up to your chest, feet together and knees apart to open your legs. Generally, a pre-labour cervix is ‘posterior’ which means pointed towards your back and this can make it difficult for the midwife or doctor to locate it during a vaginal examination, which in turn can make the procedure more uncomfortable or painful for you. It can be helpful to place a rolled-up towel underneath your bottom to tilt your pelvis forward, which will bring your cervix forward. Using gas and air can also help during the procedure. If at any stage a vaginal examination feels too uncomfortable and you want a break or for it to stop completely, you can absolutely say so. A vaginal examination should only be done if you have given your informed consent and in a way that maintains your privacy and dignity. Maintaining your privacy and dignity involves offering a chaperone, checking that you’re happy with who is the room when you have the vaginal examination (you may not want that medical student or your mother-in-law present!), ensuring that you are not exposed (i.e. by using a sheet to cover you) and ensuring that either curtains are pulled or that there’s no chance of a member of staff or a random visitor walking in mid-procedure. No-one wants to be offered a sandwich and an apple juice mid vaginal examination, trust us on that.

The purpose of these vaginal examinations, in addition to inserting the devices, medications or breaking the waters, is to assess the cervix. We wrote about vaginal examinations in an earlier blog – check it out here.

The hormone drip

Syntocinon is the last method of induction on the ladder of IOL methods – although some of the other rungs may have been skipped depending on individual circumstances. It is the synthetic version of the hormone oxytocin, and it acts on the uterus in the same way to cause contractions. It does not cross the blood-brain barrier as natural oxytocin does, therefore you do not get any of the other benefits such as the corresponding release of your body’s natural painkillers, beta-endorphins. Syntocinon is delivered via an IV line via a cannula and is only given after your waters have broken (whether that is on their own or artificially). The dose is increased incrementally, usually until there are 4 contractions in a 10 minute period.

Potential benefits:

• may stimulate contractions and help labour to progress, avoiding a caesarean birth
• can be stopped, paused or turned down if needed

Potential risks / downsides:

• can cause hyperstimulation
• very rarely, hyperstimulation may cause a uterine rupture (which is where a hole develops in the lining of the womb) or placental abruption (where the placenta comes away from the wall of the uterus before the baby is born), both of which are an obstetric emergencies that require an immediate caesarean section
• continuous monitoring (a CTG) of the baby’s heart rate is required because of the risk of hyperstimulation
• place of birth limited to a labour ward (because of the required increased monitoring)
• can make contractions feel more intense and painful (compared to spontaneous labour), requiring an epidural
• an IV line is needed to administer the medication
• increased chance of having a postpartum haemorrhage
• other common and rare side effects can be found here

A package deal

Sara Wickham writes about IOL as a ‘package deal’ in her books. Some women and birthing people who choose induction labour may go through several of the possible methods of induction e.g. a membrane sweep, then dilapan, then propess, then artificially breaking the waters and finally syntocinon. Some people will skip several steps, e.g. if the waters have broken before labour and you have agreed to an IOL, the syntocinon drip may be the next recommended step. It can be a lengthy process (we’re talking multiple days) to get your body into labour if it wasn’t quite ready for it. Choosing induction of labour also means choosing increased monitoring of the woman or birthing person and the baby in the form of regular or continuous CTG monitoring, regular vaginal examinations to check the dilation of the cervix and therefore the progress of the induction, and choosing an actively managed placental birth (with an injection) – because the process of induction is very different to the process of spontaneous labour and the hormonal interplay is disrupted, affecting the body’s natural physiology.

It is really important to know that choosing to have an IOL is not just a simple case of agreeing to whatever method is advised to start labour of. There will be several other decisions to make along the way. IOL is not like spontaneous labour, so lots of the interventions offered are to mitigate the risks of the IOL. For example, having an actively managed 3rd stage with the injection makes sense if you’ve had an IOL because there is an increased chance of bleeding after the birth. Having regular vaginal examinations (for which there is no evidence to support an improvement of outcomes for in labour) make more sense when considering an IOL because if someone has an epidural and syntocinon, they will not behave in the same way as someone experiencing a spontaneous labour – so external signs of labour progress cannot be used. CTG monitoring, whilst not shown to improve outcomes in uncomplicated labours, makes sense for a labour that is being induced with a syntocinon drip, because of the risk of hyperstimulation.

IOL is not bad per se – there are some valid reasons why are offered, which we touched upon in the previous blog. There is also no doubt that for some women and birthing people IOL is the right choice and does make a difference to their labour and birth outcomes. We are however concerned that many of the reasons that IOL are offered are not based on robust evidence and that the rate of IOL has increased significantly in the past 10 years, with the latest stats showing 33% of women in England having their labour started off artificially. Anecdotally, we hear of the risks for the rationale for IOL being heavily overstated e.g. telling someone about the risk of shoulder dystocia, without giving them the actual statistics. The risks of the IOL do not seem to be discussed with the same level of urgency. Maternity is an incredibly litigious profession and a ‘healthy baby is all that matters’ is still very much a prevalent ideology – so it is not difficult to see why IOL would be pushed in an attempt to avoid the risk of stillbirth or shoulder dystocia. This attitude however completely fails to see that IOL can and does come with risks for women, birthing people and their babies and that those risks may outweigh the benefits of awaiting spontaneous labour. It’s worth reading up on your rights, Birthrights have several factsheets – check out this one about consent. We haven’t covered all aspects of IOL, in particular women’s experiences of having an IOL, but hopefully we have provided an overview of the main methods!

We offer birth planning sessions, midwifery care for pregnancy, birth and the postnatal period and birth reflection sessions. Get in touch if you would like to know more!

Listen…

Induction of Labour with Sara Wickham – The Birth-ed podcast