Induction: Detail

This article describes induction of labour in detail. It describes why and how an induction takes place, including details of risks and complications.

Induction of labour can be an involved and lengthy process – hence there is a lot of information in this article, which will be very useful if you do end up being induced, but if not you may wish to refer to our article Induction: Summary.

What is induction of labour?

Induction is starting labour artificially – rather than waiting for the mother to go into labour naturally. Interestingly no one knows what actually starts natural labour – although we know which hormones are involved in initiating labour, we do not know the triggers for the hormones to be produced in the first place.

The principle hormones are prostaglandins and oxytocin which can both be produced synthetically and be given to pregnant women to induce labour. Approximately 20% of women in New Zealand have their labours induced.

Why would I have my labour induced?

There are many reasons why women may be advised to have their labour induced or started before the body has gone into labour naturally. No medical interventions are without potential complications however, so it is advisable to be patient and await natural events, unless you have been advised otherwise by an obstetrician. Each woman and each pregnancy must be considered individually to decide whether induction is the right option.

The most common medical reasons for induction are:

  • Overdue or post dates – your due date is only an estimate; most women go into labour 2 weeks before or after their due date. The risk of the baby getting a poor blood supply from the placenta does increase after 42 weeks of pregnancy – so although the risk of stillbirth is still low, it does increase if the pregnancy goes beyond 42 weeks. It is therefore vital to have a reliable due date, otherwise you could be advised to have induction of labour unnecessarily.
  • Pre eclampsia – this common condition of pregnancy is characterised by high blood pressure, protein in the urine and swelling of the hands, face and feet. The only ‘cure’ is to deliver the baby, therefore women with pre eclampsia are often induced when they get near to their due date.
  • Reduced growth or reduced movements from the baby – your midwife or doctor will monitor your baby’s growth and movements throughout your pregnancy, to ensure that your placenta is nourishing your baby. If the growth slows down or stops, or you are concerned about baby’s movements (the hallmark of fetal well being!) then induction of labour may be appropriate for you.
  • Diabetes – women with diabetes often have their labour induced to ensure careful planning of blood sugar control in labour and to prevent their baby growing too big for a normal, uncomplicated birth.
  • Spontaneous rupture of membranes – most women whose waters go prior to labour pains starting, will go into labour naturally within 24 hours. Sometimes this does not happen, in which case labour will often be induced over the next day or two.
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What does induction of labour involve?

There are 3 main parts to induction of labour:

Prostaglandins

Prior to the onset of labour your cervix is closed and hard and 2-3cm long. The early pains – which are often irregular and less painful – soften and thin the cervix. This process is stimulated by the hormone prostaglandin, which the body produces when labour begins naturally.

If you are being induced this hormone will be given to you to soften your cervix, if it is hard and closed. Usually prostin is used, in gel or pessary (tablet) form which is inserted into your vagina, to sit just behind the cervix where it is gradually absorbed. Meanwhile you will be asked to stay on the bed for 1-2 hours so that the gel or tablet does not fall out of place. The baby’s well-being will also be monitored continuously (via the heart beat) for at least an hour. If it has not worked the prostaglandin may be repeated after 6 hours.

By giving you this hormone to soften your cervix, the induction mimics the process of natural labour. Prostaglandins will usually cause ‘period type’ pains in the back or lower abdomen and these result in your cervix opening a little, to enable the midwife or doctor to break your waters. This stage of ‘early labour’ can be tiring and painful – showers and warm baths and massage may be helpful and if necessary the hospital midwives will give you pain relief, such as paracetamol. Ensure that you rest at this time and eat small nutritious meals to keep your energy up for labour.

Breaking the waters as part of induction

The membranes create a ‘balloon of water’ which creates a sterile environment and protects the baby inside. If the membranes have a hole in them, some of the fluid will drain out, bringing the baby’s head right down onto the cervix. This causes stronger contractions. This can also be called ‘rupturing your membranes’, ‘artificial rupture of membranes’ or ‘ARM’.

Many women fear that having their waters broken will be painful for themselves or their baby, but in fact it is not (although the contractions that follow may be more intense and painful). It is done during a vaginal examination, whereby the midwife or doctor gently inserts 2 fingers into your vagina and feels the cervix and the membranes with their fingers. An amnihook (which looks like a plastic crochet hook) is carefully inserted between the midwife’s 2 fingers, until they are able to ‘nick’ the membranes and make a hole in them to allow the water to seep out. At this stage you will feel a warm gush of fluid come from your vagina and at each contraction thereafter a small amount of fluid will leak out. (The baby is surrounded in about one litre of fluid by the end of pregnancy but it won’t come out all at once!)

As this has changed baby’s environment the midwife or doctor will check baby’s heart rate after the procedure, to check baby is still doing well. The fluid should be a pale yellow colour – the midwife will check that there is no excessive blood staining (a little pink or red streaking is normal) and that baby has not moved their bowels, which would cause the fluid to be green or yellow due to the meconium.

If your membranes do not rupture spontaneously then this will usually be done as part of an induction, as it helps to strengthen contractions and enables an oxytocin drip to be started, if necessary.

Oxytocin drip

Labour contractions happen as a result of the hormone oxytocin. This is produced by the body in normal / spontaneous labour. It can also be produced synthetically to produce labour pains and this is called ‘syntocinon’.

It will normally only be given when the waters have broken (naturally or artificially) and the cervix has had a chance to soften/ripen.

As it is not well absorbed through the stomach, syntocinon is given through a drip. You will need a luer (plastic tube) inserted into a vein in your hand or arm, which is done using a needle, then the needle is removed and the plastic tube is secured in place with sticky tape. This can be painful, so if you are afraid of needles ask about having a bit of local anaesthetic in your hand first. Once the needle is removed the luer will not hurt, but can feel uncomfortable – it will be removed as soon as your labour is over. The drug is started on a very small dose and gradually increased, ensuring that mum and baby are coping well.

The baby’s heart beat will be continuously monitored by a CTG while you are receiving the drip, as the contractions have been artificially stimulated and may become too strong. Once you are experiencing 3 strong contractions every 10 minutes (similar to normal labour) the drug will be kept at the same dose or reduced.

Sometimes induction of labour can be slow and painful, and being attached to a drip and a monitor does reduce your ability to move around and get comfortable. Your lead maternity carer will advise you about pain relief – many women who are induced have an epidural, as the process can be very long and tiring.

What are the risks and complications of induction?

Labour is essentially a normal process and any interventions or interferences with that normal process carry risk of complications.

There is a risk that the baby will not react well to the hormones or having the waters broken and that they will show signs of distress (lack of oxygen) through the heart rate or moving their bowels inside you (baby may pass meconium, causing the fluid to become green / yellow colour). Often the signs of distress can be transient, but if severe this may result in an emergency caesarean section.

Once labour has been initiated – particularly once the waters have broken – it is not usually safe to stop the procedure, due to risk of infection to mother and baby. Therefore, if labour is very difficult to initiate or if it starts then stops, you may end up needing an emergency caesarean.

If your waters are broken before baby’s head has moved down in to your pelvis, the cord may come down into the vagina – and this will affect baby’s blood supply. Once again the result would probably be a caesarean section.

What can I do to prevent induction of labour?

Try to avoid induction of labour if you can – but life is a balance of risks and some medical conditions in pregnancy carry a greater risk than induction of labour, in which case this will be the best option for you at that time.

Ask about having a ‘membrane sweep’ prior to induction of labour. This is a vaginal examination that aims to stimulate your body to produce its own prostaglandins and therefore start labour naturally. It can be uncomfortable, but it lessens your chance of needing induction of labour.

If your pregnancy goes on past your due date try having sexual intercourse to initiate labour – particularly if you stay lying down afterwards to keep the semen close to your cervix, as it contains natural prostaglandins!

We all get fed up towards the end of pregnancy due to tiredness and discomfort. Seek help of friends / family / whanau at this time and try to stay patient and rested to allow your body to go into labour naturally… just like animals we will only go into labour when we feel safe and secure!

If you do need to have your labour induced then seek advice from your carers at that time on how to promote the natural process of labour, whilst working within the constraints of continuous monitoring; for example, upright positions that aid contractions, or what to eat and drink during the early stage of induction to aid your body to respond well to the hormones.

Don’t ever be afraid to ask questions and to seek support – you will only labour well if you feel rested and safe.

Helpful Induction Websites

www.babycentre.co.uk

This UK website contains factual information on the process of induction of labour and a section on membrane sweeping.

Paula Skelton

Paula Skelton is a qualified NZ nurse and midwife, a midwifery & childbirth educator and the mum of three lovely girls.

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