Important: This is intended as general information only. It may not apply to your specific situation. It is not a substitute for medical advice. If you have a question or concern, please raise it with me at your next appointment or contact me sooner if it's urgent.
Induction of Labour
Induction of labour (IOL) involves using medications and/or procedures to start your labour. I may suggest this if ending the pregnancy is safer for either you or your baby (or, to put it another way, if continuing the pregnancy is dangerous for either of you).
Reasons for having an induction include:
- Maternal medical problems – a maternal medical condition may have negative effects for the mother, the baby or both. Obviously there are lots of possibilities here but common conditions include pre-eclampsia, diabetes and women taking blood thinning medications. In some situations, it may be necessary to control the timing of the delivery to coordinate other treatments.
- Concern for fetal wellbeing – if there are signs that the baby is not getting everything he or she needs from the placenta, particularly if the baby is not growing appropriately
- Fetal medical problem – if we know that the baby has a health problem (for example a heart abnormality), it may be sensible to control the timing of delivery. This way, we can make sure that we have everything that we need on hand so that the baby gets the best available treatment immediately.
- Prolonged pregnancy – the most common indication, more about this later
- Prelabour rupture of membranes – this refers to the situation in which your waters break but you don’t go into labour in the next 24 hours or so
- The way in which labour is induced depends on how ‘ready’ your body is to labour. This is determined by examining your cervix. Essentially, what we try to do is mimic the process of spontaneous labour.
In a spontaneous labour:
- Your body produces prostaglandins – these hormones start preparing the cervix by making it softer, shorter, move forward and even start to open up. They also make the uterus more sensitive to oxytocin
- Your brain produces oxytocin – this hormone makes the uterus contract
- Your waters break (membranes rupture) – this makes contractions stronger and more effective. The waters may break before or after the contraction start
In an induced labour, we try to mirror this process and ‘coax’ your body into labour. The exact sequence of events depends on how ‘ready’ or ‘favourable’ your cervix is – that is, whether it has started to change already or not. The most common methods of induction include:
This hormone gel is inserted into the vagina. Before inserting the gel, your baby is monitored to make sure he or she is healthy before we start. After the gel is inserted, you need to stay lying down for 45-60 minutes. As the gel is absorbed, most people start to contract. For some women this will be mild period-pain type cramps and for others it will be strong labour-like contractions. This may all settle down after a few hours or it may progress into established labour. Usually, we give a dose of prostaglandin in the evening and wait to see what happens overnight. If a women hasn’t gone into labour overnight, hopefully her cervix will be more favourable by the next morning. In some cases, we need to give a second dose of prostaglandin.
Artificial rupture of membranes (ARM)
This can only be done if the cervix is already slightly open. It involves a vaginal examination and inserting a thin pair of tweezers or a thin hook into the vagina to make a hole in the sac of fluid around the baby. Breaking the waters by itself doesn’t actually hurt but many women find vaginal examinations uncomfortable.
A synthetic hormone that is identical to the hormone produced by your brain is used and it makes your uterus contract. It is given as a slow continuous intravenous infusion. We start at very low dose and gradually increase the dose until you are contracting strongly
Whether you need one, two or all three of these options depends on your starting point and how your body reacts to the medications.
Induction for prolonged pregnancy
This is the most common reason for induction, particularly for women having their first baby. It’s considered ‘normal’ to go into labour anywhere between 37 and 42 weeks gestation. However, the average placenta seems to last about 42 weeks and we know that, as the placenta ages, it’s functions starts to slowly decline. As the placenta starts to decline, the risk of the baby becoming distressed in labour (and therefore needing an emergency caesarean section) increases. Also, as the placenta starts to decline, the small risk of stillbirth starts to rise, especially after 42 weeks gestation.
Large international studies have found that, by inducing labour between 41 and 42 weeks gestation, we can actually reduce the caesarean section rate (ie more women have vaginal deliveries) compared to waiting for spontaneous labour. Of course, the other benefit is that we deliver women before they reach that higher-risk time for stillbirth.
Obviously, there is a bit of a balancing act here. We don’t want to intervene too early and induce people who don’t need it. Equally, we don’t wish to expose babies to the risks of declining placentas or women to the risks of unnecessary emergency surgery. The tipping point seems to be around 41 and ½ weeks (or 40 weeks, 10 days) gestation.
Of course, all of this is based on population averages about the way in which placentas behave. They don’t necessarily predict how your baby’s placenta will behave. There are probably some placentas that function well beyond 42 weeks gestation, although we don’t have a good way of measuring this so nobody sensible wants to take that risk. Certainly, there are some placentas that start to decline before 42 weeks. As we get close to and beyond your due date, I will monitor your baby a little more closely to detect any early signs that this is occurring, just in case we need to do something before 41 ½ weeks.
Induction for prolonged rupture of membranes
For most women, contractions start first and the waters break at some stage during the labour. For some women, however, the waters breaking is the first sign that anything is happening. In most cases, the labour will commence in the next 24 hours or so. In a small number of women, labour does not commence in this time and these women are said to have ‘prolonged rupture of membranes’. Once the waters have broken, the baby is exposed to all the bacteria inside the vagina. There is a small risk that the bacteria can climb up into the uterus and set up an infection within the uterus and the amniotic sac. This is known as chorioamnionitis and it is bad for the mother and the baby. For this reason, if you are in the situation that your waters have been broken for more than 24 hours and you are not in labour, I will recommend that you are induced. In this situation, we use an oxytocin infusion.
These are the questions I am most commonly asked about induction of labour
Are there any risks of induction?
Yes, all procedures and treatments carry risks, like just about everything else in life. The important thing to remember is that I will recommend an induction only when I think the risks of continuing the pregnancy are greater than the risks of induction.
The drugs used to induce labour can cause the uterus contract too much. This is called uterine hyperstimulation and it is uncommon because we try to start slowly and progress gradually. If necessary we can stop the drugs and give a medication to stop the uterus contracting.
Sometimes, no matter how hard we try, we just can’t convince your body that it wants to go into labour. This is called a ‘failed induction’ and usually means that you will need a caesarean section.
Very rarely, when the waters are broken, the umbilical cord can fall out into the vagina in front of the baby’s head. This is known as a cord prolapse – it is an emergency that requires an immediate caesarean section. We generally don’t try to break the waters unless the head is engaged (low in the pelvis) to avoid this situation.
Am I more likely to have a caesarean with an induced labour?
It depends on the reason that you are being induced. As discussed above, women who are induced for a prolonged pregnancy are actually more likely to have a vaginal delivery with induction than without. For some indications, however, the risk of caesarean does increase, particularly if you need to be induced well before your due date (before your body is ready). It’s important to remember, however, that many of the reasons we suggest inductions (such as sick mothers, babies not growing properly) make you more likely to need a caesarean in and of themselves. So, it can be hard to know whether the induction or the underlying condition is the reason for the caesarean.
Are induced labours slower/faster/more painful than spontaneous labours?
Depending on who they’ve been talking to, many of my patients think that an induced labour is either longer or shorter than a spontaneous labour, and possibly more painful. In my experience, spontaneous labours and induced labours are both quite unpredictable. Some are long and hard and others are quick and less arduous. In either case, it’s impossible to know what any given spontaneous labour would have been like had it been induced and vice versa. There are sometimes situations in which patients need to be induced but we think that, because of their particular situation, it’s likely to be a long difficult process. There are a few different ways of managing this situation. If you find yourself in this position, I will talk to you about the various options and we’ll make a decision together about the best course of action.
I’ve had a previous caesarean section and want to have a vaginal birth this time. Can I still be induced?
It really depends on your cervix. It may be possible but we’re a bit more limited in our options for inducing women who have had previous caesareans. We cannot use prostaglandins and can only use oxytocin very carefully and in certain circumstances. Performing an ARM is fine but, of course, this can only be done if the cervix is already a little open.
Can I try a ‘natural’ method of induction?
You can certainly try but most of these old wives tales are just that. There is no evidence that they work and, for most of them, no reason why they would work. (Believe me, if drinking tea could avoid the need for inductions, obstetricians would recommend it – it would save us a lot of work!). Remember that most people will go into labour naturally at some point so it may appear that the particular trick they tried yesterday worked, when in fact they were always going to labour at that particular time. Since the evidence is poor, at best, my suggestion is only try things you actually find pleasant to do. If you enjoy reflexology foot massages, for example, then go for it – a foot massage is very unlikely to make you go into labour, but it may be a nice way to spend a couple of hours in the late third trimester. Castor oil sounds terrible (who would want nausea and diarrhoea in the late third trimester?) so if I were you, I’d avoid it.
What about a stretch and sweep?
A stretch and sweep refers to a procedure in which an obstetrician or midwife inserts a gloved finger into the cervix and gently tries to separate the amniotic membrane from the cervix. This releases prostaglandin and can be enough to cause labour. Studies have shown that this technique works reasonably well – on average, for every 8 stretch and sweeps performed, one induction will be avoided (ie one extra woman will go into labour). It’s quite safe although can be uncomfortable and can cause some bleeding from the cervix (this is not at all dangerous but can be quite alarming). I routinely offer a stretch and sweep from 39 weeks gestation for women who want one.