The risks associated with induction of labour

The process of IOL consists of three key stages (note, not all women will need to go through each stage to get into established labour. However if you haven’t had a baby before it is more likely that you will need to. The most used method to induce labour is by starting off with prostaglandins to soften the cervix. However, sometimes a different method using a balloon catheter is indicated. This will be explained separately: 

1. Prostaglandin comes in the form of Propess or Prostin to help to soften your cervix and open it up enough so that the next stage of the induction is made possible
2. Releasing your waters can help to start contractions and/or make them more regular and efficient during an induced labour, however this is not routinely advised in spontaneous labour (ref. 2)
3. Syntocinon is an artificial version of the hormone Oxytocin needed to make strong, regular tightenings, if the first two stages haven’t achieved this.

Prostaglandin stage

Before administering any prostaglandin, the midwife will need to perform a vaginal examination in order to assess your cervix and decide what the first step of the induction should be. When assessing the cervix the midwife is taking into account the following aspects:

• Whether the baby’s head is high or low in the vagina
• How soft or firm the cervix feels
• Whether the cervix is behind the baby’s head, or near the front
• The length of the cervix
• How open the cervix is 

After assessment, if it is found that your cervix is already ‘ripe’ (soft, low and open enough), then the prostaglandin stage may be skipped and your induction will be started by releasing your waters instead. However, the majority of women will need the prostaglandin first. The prostaglandin will be inserted into the vagina and for 30 minutes after this the midwife will advise you to stay lying down. Your baby will need to be monitored during this time.

The possible side effects of prostaglandin are:

• Nausea/vomiting
• Diarrhoea
• Slight increase in temperature
• Lowering of your blood pressure
• Increased need for pain relief
• Uterine hyperstimulation (having too many tightenings)
• Fetal distress
• Very rarely uterine rupture, which would need immediate delivery of baby
• Vaginal soreness/dryness which can make future vaginal examinations uncomfortable

The prostaglandin will stay in place for up to 24 hours. The midwife will ask to listen to your baby’s heartbeat at regular intervals, the frequency will depend on the reason you are being induced. If you haven’t gone into labour, then a vaginal examination will be offered after 24 hours to see if your cervix has opened up enough to move to the next step of the induction – to break your waters. If the midwife thinks this would be possible and when delivery suite has capacity then you will be transferred to delivery suite for this to happen. 

A vaginal examination may also be offered if you are having strong, regular tightenings and you are feeling you need some strong pain relief. If your cervix hasn’t opened up enough for your waters to be released, the midwife will talk to the doctor about the next step forward.  This will probably be to have a new prostaglandin inserted for another 24 hours. If there is no change after a second prostaglandin it may be recommended that you have a different type of prostaglandin that is released over fewer hours, or it may be decided that the induction process hasn’t worked for you. In this case, depending on the reason you are being induced and on how you feel, you may be able to go home and then re-start the process in a couple of days or you may be offered a caesarean section. 

Releasing your waters

This is when the midwife or doctor inserts two fingers into the vagina and then slides a long, flat plastic ‘amnihook’ along their fingers and into the opening of the cervix where the hook then pierces the amniotic sac which surrounds baby, and the liquor (water) is released. The midwife will keep their fingers there for a minute or so to ensure that baby’s head stays well down in the pelvis. 

Babies can sometimes have some heart rate changes during this procedure, so will need to be monitored on the CTG monitor for half an hour after releasing your waters, this provides a long, printed recording of baby’s heart rate. If baby’s heart rate is normal then the monitoring can be discontinued. 

Risks of having your waters released include:

Increased risk of infection - Once the protection of the amniotic sac is broken, this is further increased if you then go on to have lots of vaginal examinations

• Vasa Praevia - Very rarely there may be a blood vessel running through the amniotic sac.  If this was torn by the amnihook it may cause excessive blood loss and would need immediate delivery of the baby.
• Cord prolapse - If baby’s head isn’t engaged well into the pelvis there is a chance that the baby’s cord can slip past the baby’s head and into the vagina. If this happens it is an emergency and requires immediate delivery of baby.
• Scratch to baby’s head - Sometimes if the amniotic sac is tightly against baby’s head there is a possibility that baby’s head may have a little scratch on it from the amnihook

It is usually then advised to wait 2 hours after having your waters released, to see if tightenings start up by themselves. If tightenings do not become strong and regular during this time, the hormone drip ‘syntocinon’ will be advised. However, this is your birth and if you feel it would be beneficial to have more time to let tightenings establish before starting the drip then you can have a chat with your midwife/doctor to discuss the benefits and risks and make an individualised plan.

Syntocinon

Syntocinon is a synthetic version of the hormone oxytocin that is released in a spontaneous labour. It helps to create strong and regular tightenings. 

If you decide that starting the syntocinon drip is the right pathway for you, then a cannula will need to be inserted into your hand.  This involves inserting a needle into your vein in order to site a small plastic tube - once the tube is in place the needle will be removed. This allows the hormone to be administered straight into your blood stream. 

The drip is started with very small volumes of syntocinon and increased every half an hour until you are having around 3-4 tightenings in every 10 minute period. Everyone responds differently to syntocinon, some women will start tightening quickly but some will need more of the drip before contracting. For a few women syntocinon doesn’t work for them.  This is more likely if you’re body isn’t ready for labour yet. 

To check that the tightenings are effective at opening up your cervix, your midwife will offer you a vaginal examination 6 hours after starting the drip or 4 hours after regular, strong tightenings and then 4 hourly from there on. 

Because the syntocinon drip has potential to make baby distressed, your baby’s heartrate will need to be continuously monitored.  This involves having two straps around your tummy to hold on the discs which monitor the heartrate and the tightenings - these discs are connected to the main monitor with electrical wires. Being continuously monitored can be restrictive to your natural instinct to move around in labour and we know keeping mobile helps labour to progress. Your midwife will support you as much as possible and try to facilitate your preferred position. 

For further reading on keeping mobile during labour, see below: https://evidencebasedbirth.com/evidence-birthing-positions/

Risks associated with syntocinon include: 

Increased chance of caesarean section

There is a higher chance of having a caesarean section if your labour is induced. If this is your first baby the chance ranges from 26.5% to 39.9% compared to 12.5-17.5% % if your labour started on its own (ref 3,4). The reason for first time mother’s being at increased risk maybe due to the fact that a woman’s first labour can take longer.  When you are induced there is an expected rate of progress in labour, which is sometimes harder to meet during a first labour. Risks associated with caesarean sections are included in an appendix at the end of the booklet. At Wye Valley Trust in 2021, 29% of all inductions led to a caesarean section.

Increased chance of malposition

Malposition is when a baby is in a position that isn’t ideal for a vaginal birth, for example, baby’s back is towards your back, or baby’s head is at an angle, meaning the head isn’t creating equal pressure on your cervix. In a labour that starts on its own, baby usually changes his/her position between tightenings to try and find the best position ready for birth, and at the point of being fully dilated there is sometimes a slowing down of tightenings to enable baby to do this even more so. However, during an induced birth there isn’t a feedback loop with baby’s needs and induced tightenings can be stronger and more regular, therefore baby might not have enough time to make those adjustments prior to birth (ref. 5). These adjustments become crucial at the point of birth, which is why there is an increased risk of shoulder dystocia when using syntocinon (RCOG, 2012). This is an emergency and requires certain manuevres to help deliver baby’s body. 

For more reading on optimal positions in labour and birth, see here:

Baby Positions - Spinning Babies® 

Perineal tearing

When you are birthing your baby’s head during an induction of labour it is more likely that you will have some perineal tearing (tearing involving the skin and muscle around your vagina and anus). This is because syntocinon can often make the birth of baby’s head faster than spontaneous labour and this is associated with a higher chance of tearing (ref. 6). 

Your midwife will discuss with you whether you would like a ‘hands on’ birth, where the perineum is supported and some gentle counter-pressure is applied to baby’s head during the birth in order to slow the birth of baby’s head, which may reduce the chance of tearing. 

Also, induction increases the chances of having an instrumental birth (ventouse or forceps) which in turn increases the chance of perineal tearing (ref. 7). 

For more reading on reducing the chance of perineal tearing, read here:

Perineal massage in pregnancy | Pregnancy, Worries and discomforts articles & support | NCT

Perineal Protectors? | MidwifeThinking

Complications for baby at birth

Evidence tells us that a baby is more likely to need help with their first breaths at birth if the labour has been induced (ref. 4) and their chance of developing cerebral palsy is more (ref. 7).  A possible reason for this is that syntocinon increases the chance of hyperstimulation (too many tightenings) and if this isn’t recognised or managed well then could lead to fetal distress. However, your midwife will monitor your tightenings and reduce the syntocinon if they have concerns. 

Excessive bleeding

The chance of bleeding excessively once baby is born is increased when your labour is induced (ref. 8). This is especially true if you have been on the syntocinon drip for a long time as this can cause your own oxytocin receptors to become desensitised and stop reacting to further doses of syntocinon. This becomes a problem when baby is born and the muscles in your womb need to clamp down to prevent the blood vessels bleeding excessively. If you do bleed excessively it will be treated as an emergency in which other drugs are used to help reduce the blood loss as well as uterine massage. 

Fluid retention

Syntocinon can cause you to ‘hold on’ to any water you drink or any fluids you receive during labour. This can result in swelling, usually in your hands, ankles and feet. Your cervix can also become swollen which could potentially hinder dilatation. Baby can also suffer with fluid retention.  This becomes an issue because his/her birth weight may be higher than it would have been. Once baby has lost the extra fluid through urinating, it may appear as though baby has lost weight or has poor weight gain when next weighed. This may then lead to the suggestion that baby should go on a feeding plan which is potentially unnecessary.

Breastfeeding problems

It is thought that the use of syntocinon can de-sensitise a woman’s oxytocin receptors which are needed for the let down of milk from the breast. It can also alter the baby’s instinctive behaviour, in turn reducing their feeding responses. Studies have found that women who had syntocinon during labour are twice as likely to feed their baby formula whilst in hospital and are three times less likely to initiate breastfeeding during the first 4 hours of baby’s life. (ref. 9). However, in Wye Valley NHS Trust we have specialist maternity support workers on the postnatal ward and in community who can help you achieve your breastfeeding goals. Postnatal depression and anxiety, a link has been found between women who had syntocinon during labour with depression and anxiety during the first 12 months after birth. 

Possible reasons for this is the effect syntocinon has on the oxytocin system of the mother and the possible difficulties with breastfeeding as outlined above (ref. 10). 

Increased need for pain relief

In a labour where syntocinon isn’t used, oxytocin is released from the brain and into the blood stream, when there is a high level of oxytocin in the brain it helps you to release endorphins (natural pain relief). Because syntocinon goes straight into your blood stream it doesn’t cross the brain barrier, which means that tightenings can feel stronger than they would in a spontaneous labour. Syntocinon also tends to create longer tightenings with less space in between. These two factors can lead to an increased need for an epidural which has been found to reduce the amount of oxytocin produced by the mother (ref.11). 

Induction of labour using a balloon catheter

A balloon catheter is when a catheter (plastic tube) is passed through your cervix, (a speculum will be used in order to see your cervix) and the small balloon is inflated with 30mls of water so it sits between the bag of waters and the base of your womb. This will hopefully encourage your body to release their own prostaglandins to soften and open your cervix and as the cervix opens it may help oxytocin to be released to create contractions. 

This method of induction isn’t used as much as using prostaglandins, but can be a good option when wanting to avoid the chance of hyperstimulation (creating too many contractions) such as if you have had a caesarean section before, where there is an increased chance of your scar separating. 

A review of research shows that this method of induction appears to be just as effective as vaginal prostaglandins as well as having less risks associated with it, however the quality of evidence is low. 

Possible side effects/risks 

Abdominal cramping

You may experience lower abdominal cramping and feel uncomfortable. However, women’s feedback suggests it is less uncomfortable to have a balloon catheter than to have vaginal prostaglandins (ref. 12). 

Accidental releasing of your waters

When inserting the catheter there is a small chance of accidently releasing your waters.  However, as this is the next stage in the induction process then it isn’t seen as a problem. 

Difficulty removing the catheter

It is very rare but sometimes it can be difficult to remove the catheter which can end up being very uncomfortable. 

Malposition

Due to the balloon being positioned between the baby’s head and the base of the cervix, there is a small chance that it can push the baby’s head further up and the baby can move into a position that isn’t ideal for birth. For the same reason, it can also increase the chance of the cord coming out first when the waters break.  This is an emergency and requires immediate delivery of the baby (ref. 12). 

Induction of labour at home 

If there is not an immediate concern for your or your baby’s wellbeing then starting your induction at home may be an option for you. It would mean you could have your initial monitoring and insertion of your propess in hospital and then go home for up to 24 hours to await contractions. You would be able to phone triage to update us on what is happening and if tightenings become strong and regular, we would advise you to return to the maternity ward to monitor baby. If you needed a further 24 hours of propess, it would be recommended that you stay in hospital for this. 

As part of the induction of labour policy, the following women/situations would be ideal candidates for an outpatient induction of labour: 

• Where there are no significant concerns about about you or your baby
• You are between 41-42 weeks pregnant
• You have a singleton pregnancy
• Your baby is head down
• You are not anaemic
• Your BMI is between 18-35
• You have had no more than 3 births before
• You have your own transport and don’t live further than 30-45 minutes from hospital
• You have a birth partner with you the whole time
• You have a working mobile phone or landline
• There are no concerns about your safety at home
• The monitoring of baby before and after having the propess inserted, is normal