What happens during an induction of labour? What does this mean?

7 things to know about induction of labour:

1.   There are many reasons for induction of labour, but it is usually offered to deliver a baby early when the risks of remaining pregnant are higher than delivery of the baby.
2.   Induction is broken down into two main parts – firstly the cervical ripening stage and followed by artificial rupture of membranes and use of a hormone drip.
3.   The cervical ripening stage is the process of changing the cervix using artificial means enough to be able to rupture the membranes. This can be done using hormones, or mechanically, using a balloon, for example
4.   When the cervix is open enough, then you transfer to labour ward to have the membranes ruptured. This is done with a small plastic hook
5.   After the membranes are ruptured, a hormone drip is used to start contractions.
6.   Induction of labour takes longer and is more painful than a labour which starts naturally.
7.  The time it takes varies but expect it to take, from admission, around 36 hours. It can be shorter or longer than this.

What is the induction of labour?

Induction of labour is the name given to the process of starting a labour off artificially. It is a common procedure and about 20-25% of women will have their labour started rather than waiting for it to start naturally. There are lots of possible reasons to induce a labour but it usually happens because it is better to have the baby born sooner rather than just waiting for labour to start by itself.

Why might I need to be induced?

Common reasons include if the baby is not growing as much as it should be, or if you develop a complication like pre-eclampsia, or if you have gone a week or more beyond your due date. Usually, induction of labour will be discussed and explained to you by either a doctor or a midwife. They should explain why they are offering induction of labour, rather than waiting for labour to start by itself. They should also explain the risks and benefits, specifically to your pregnancy and the reason labour is being induced.

What are the benefits of having an induced labour?

The main benefit of induction is to shorten the pregnancy and to avoid complications of pregnancy that might happen should you remain pregnant. The disadvantages are that, compared to a spontaneous labour, an induced labour will usually take longer and often be more painful. It can also therefore mean that you stay in hospital for longer. There is, however, good evidence that, compared to waiting for labour to start by itself, there is a lower chance of needing an emergency caesarean section, and no difference in whether the baby needs to be born by ventouse or forceps. There is also no difference in the risk of bleeding. However, this is not the same as comparing an early induction of labour with a spontaneous labour which also occurs early. In this comparison, there are usually fewer labour complications if labour starts on its own, but this is not the correct comparison to make. The hospital may have access to local figures on its own labour outcomes from induction of labour and you may find this helpful. There are some particular risks to induction of labour if you have had a caesarean section before, and I will discuss these in a different blog.

 The doctor and midwife should also explain the process and when the induction will start, and what arrangements will be made for you to attend and have the process started.

What happens if I do get induced?

There are lots of different ways to induce a labour now and the exact process will vary with individual hospitals, so make sure that you are sure that you understand how it will happen for you. All inductions of labour start with an attendance at hospital and monitoring of the baby’s heart rate using a special heart rate monitor called a CTG. If the CTG looks normal, then the induction process will start. The first step is to examine the neck of the womb. Sometimes, the neck of the womb (cervix) has already opened up a bit and it is possible to rupture the membranes. However, this is fairly unusual and most women need some treatment to open up the cervix enough to be able to rupture the membranes. This is a process known as ‘cervical ripening’. I always find this is a bit of an unpleasant term, but it just means getting the cervix ready for active labour, a bit like the latent phase explained in the blog on normal labour. There are many ways of doing this and different hospitals have different processes. Options include:

•   Using a medicine given vaginally, known as a prostaglandin. This is a synthetic version of a hormone that your own body produces when it is getting ready for labour. Versions of this include tablets, gels (Prostin) or a 24 hour pessary (Propess). There are a small number of hospitals using a pessary called misoprostol but this is unusual (this can in theory be given by mouth but it tends to cause more side effects that way). Prostaglandin is generally a very safe medicine but it can cause vaginal soreness, and some people are, rarely, very over sensitive to it and the womb contracts too much and too quickly. This is called hyperstimulation. The prostaglandin aims to soften, shorten and open up the neck of the womb enough to be able to rupture the membranes. Sometimes, the prostaglandin starts the labour off on its own, although this is relatively uncommon.  Propess is a prostaglandin preparation that sits in the vagina for 24 hours (usually you cannot tell it is there). Prostaglandin tablets or gels are given every 6 hours.

• There are also several mechanical ways of achieving the same changes in the cervix. These are thought to be a bit more gentle as they rely more on your body producing its own hormones. These include:
  • •  A cervical balloon which is a small tube (catheter inserted into the cervix) and then a balloon gets inflated either side of the cervix to provide physical pressure.
  • • Another method that can be used in a similar way is called Dilapan. This is a small dilator system of 4-6 rods which sits inside the cervix and gradually pushes it to encourage the cervix to open.
  • • Both these options are more uncomfortable to insert that the prostaglandins, and can sometimes feel more uncomfortable until they are removed. The catheter balloons stay in place for around 12 hours or until they fall out. Dilapan is usually used for around 12-15 hours. In both cases, it is hoped that artificial rupture of membranes is possible after this time.

 Some hospitals offer outpatient induction of labour for women who meet certain criteria. Usually this is offered with Propess. However, most women need to be admitted to hospital for induction of labour. Often you will be on an antenatal ward but some women are admitted straight to the labour ward.

What happens when my labour begins?

After the cervix is ready for the membranes to be broken, then you will be transferred to the labour ward. There is often a wait for this as labour wards are commonly busy places and there needs to be both a room and a midwife available. Ideally, you should be transferred as soon as possible.

After you arrive on labour ward, the midwife will monitor the baby again and usually a drip will be placed into a vein, ready for labour. The midwife will then rupture the membranes with a plastic hook, known as an amnihook. This can sometimes feel a bit sore and uncomfortable but this depends on how ready the open the cervix is.

You will then be offered the option to see if the contractions start by themselves over the next hour or two, or the option to start the drip containing the hormone straight away. Most women tend to need the drip regardless, but mobilising for a while can be helpful. Once the drip is started, then the baby needs to be monitored with the CTG continuously (see the blog on the CTG).

The drip is a hormone called oxytocin, or the brand name for it is Syntocinon or ‘Synto’. It is also sometimes called IVO. This is given at a very low dose and is increased very slowly, every half hour until you are contracting regularly, at around 3-4 contractions in 10 minutes. This can take some time, especially in first labours. 

You will then also be offered a vaginal assessment after 4 hours of regular contractions. Your midwife will also talk to you about pain relief options, as syntocinon tends to produce contractions that are more painful than in a natural labour. It can take a while until the baby is born, and this depends on how ready your body is to go into labour.

Sometimes the first stage of labour, which is until the cervix is 4cm dilated can be slow, only 1-2 cm every 4 hours. However, after 4 cm, it would be expected that the labour would progress more quickly, usually around 0.5-1cm every hour.  All hospitals are different, but admission to delivery time can, on average, be around 36 hours.