IOL – Induction of Labour

Induction of labour (IOL) means attempting to make labour happen by membrane sweep, using drugs or by rupturing your membranes (breaking your waters) when your body hasn’t gone into labour naturally. I have seen women arrive to maternity time and time again for IOL without having the first clue of what it means or why exactly they are being induced. This will hopefully make you better informed about IOL and why you may or may not decide to proceed with it.

What you need to know about IOL

It’s your choice! You have to consent to being induced. A doctor saying “We need to induce you for x,y or z” is not good enough. What should happen is your healthcare provider lets you know that they would recommend induction of labour for you because of x, y or z. Then they should go on to explain the benefits of IOL for you, the risks of IOL for you, the process of IOL and the alternatives to IOL. Then YOU get to make the decision on whether you want to proceed with IOL.

There are many reasons a healthcare provider might recommend IOL for you, the more common ones are:

  • gestational diabetes
  • reduced fetal movements or other concerns for baby such as reduced growth
  • post dates
  • maternal condition such as pre-eclampsia
  • pre-labour SROM (waters breaking without any contractions for 24 hours)

Post dates

The most common reason for IOL is post dates and this is what I will focus on in this post for low risk pregnancies. The internationally agreed average length of a pregnancy is 40 weeks from the first day of your LMP (last menstrual period) but how accurate is this? It’s not! LMP is not an accurate way of determining a due date as different women have different length cycles, implantation can occur early or late and sometimes women just don’t know what date their LMP was especially in unplanned pregnancies. To accurately determine a due date, a dating scan should happen around 12 weeks gestation (Moken et al., 2014). Due to a lack of resources in healthcare in Ireland, some hospitals don’t offer this as standard. Add to this a recent study (Jukic et al., 2013) that finds pregnancy length naturally varies by up to 5 weeks so some women might naturally go into labour at 37 weeks and some might not go into labour until 42 weeks or beyond. This means that post dates for one woman could be 39 weeks and for others it could be 43 weeks or beyond. So inducing labour for post dates is a bit more complicated than you may first have thought. However, most hospital IOL policies are loosely based on the NICE guideline on Induction of Labour (see here) which recommends IOL between 41 and 42 weeks.

Risks of IOL

  • hyperstimulation – uterus over-responds to drugs used for IOL and contractions happen too frequently resulting in fetal distress.
  • failed induction – the drugs don’t work! In these cases, where there are no other clinical complications, a further attempt at IOL should be offered after a rest period. If this fails also then usually caesarian section is the next step.
  • cord prolapse – this is always a risk of artificial rupture of membranes (breaking the waters) and is an obstetric emergency requiring expedited delivery of the baby by caesarian section if necessary.
  • need for additional pain relief – usually as a result of a combination of strong contractions and continuous fetal monitoring meaning it’s more difficult to mobilise. Continuous fetal monitoring in linked with an increased risk of caesarian section. The use of epidural increases risk of instrumental delivery.
  • post partum haemorrhage (Selo-Ojeme et al., 2010)
  • recent studies have shown increased risks of babies being in poor condition at birth following IOL using syntocinon (Selo-Ojeme et al., 2010)
  • for first time mothers, risk of caesarian section is increased by IOL (Ehrenthal, Jiang, and Strobino, 2010). And a large population based Swedish study by Ekeus and Lindgren (2016) shows IOL contributes to a large increase in caesarian section and vacuum extraction rates in all women.

Benefits of IOL

  • In large for dates babies, IOL can reduce risk of caesarian section (Boulvain et al., 2015)
  • Some literature claims that IOL reduces risk of caesarian section in general (Wood, Cooper, and Ross, 2013)
  • It is widely known that induction of labour at term very slightly reduces the risk of stillbirths (Hedegaard et al., 2014). However, the absolute risk of stillbirth is small, here I have broken it down by gestation as follows – 39 weeks gestation 0.12%, 40 weeks gestation 0.14% and 41 weeks gestation 0.17% (Rosenstein et al., 2012).
  • IOL at or beyond term can reduce occurrence of meconium aspiration syndrome, however IOL does not reduce admissions to NICU (Gulmezoglu et al., 2012)

Alternatives to IOL

Just wait for labour to start naturally – this is called expectant management. You will be expected to have regular scans to make sure baby is ok and your placenta is functioning properly. Obviously if there are decreased fetal movements or any other concerns then this is not appropriate for you. But if you have a low risk pregnancy and would prefer to wait for things to happen naturally then this is your decision. You might also decide you want to wait until you are 42 weeks as opposed to 10 days over which seems to be the magic date in Ireland for IOL. Whatever your decision, as long as you are fully informed of the risks and benefits of your choice then it’s your decision to make! The key is to ask lots of questions so you have all the information.

If you are going to wait it out and want ideas on how to fill your last few days or weeks, check out my post on how to enjoy your third trimester!

I will post again with information on the process of IOL if you do decide this is what you want or if it is medically indicated for you due to health reasons concerning you or baby.



Boulvain, M., Senat, M., Perrotin, F., Winer, N., Beucher, G., Subtil, D., Bretelle, F., Azria, E., Hejaiej, D., Vendittelli, F., Capelle, M., Langer, B., Matis, R., Connan, L., Gillard, P., Kirkpatrick, C., Ceysens, G., Faron, G., Irion, O., Rozenberg, P. and Groupe, de (2015) ‘Induction of labour versus expectant management for large-for-date fetuses: A randomised controlled trial’, Lancet (London, England)., 385(9987), pp. 2600–5.

Ehrenthal, D., Jiang, X. and Strobino, D. (2010) ‘Labor induction and the risk of a cesarean delivery among nulliparous women at term’, Obstetrics and gynecology., 116(1), pp. 35–42.

Ekéus, C. and Lindgren, H. (2016) ‘Induced labor in Sweden, 1999-2012: A population-based cohort study’, Birth (Berkeley, Calif.)., 43(2), pp. 125–33.

Gülmezoglu, A., Crowther, C., Middleton, P. and Heatley, E. (2012) ‘Induction of labour for improving birth outcomes for women at or beyond term’, The Cochrane database of systematic reviews.

Hedegaard, M., Lidegaard, Ø., Skovlund, C. and Mørch, L. (2014) ‘Reduction in stillbirths at term after new birth induction paradigm: Results of a national intervention’, BMJ open., 4(8).

Jukic, A.M., Baird, D.D., Weinberg, C.R. and McConnaughey, D.R. (2013) ‘Length of human pregnancy and contributors to its natural variation’, Human Reproduction, 28(10), pp. 2848–2855. doi: 10.1093/humrep/det297.

Morken, N.-H., Klungsøyr, K. and Skjaerven, R. (2014) ‘Perinatal mortality by gestational week and size at birth in singleton pregnancies at and beyond term: A nationwide population-based cohort study’, BMC Pregnancy and Childbirth, 14(1), p. 172. doi: 10.1186/1471-2393-14-172.

Rosenstein, M.G., Cheng, Y.W., Snowden, J.M., Nicholson, J.M. and Caughey, A.B. (2012) ‘Risk of Stillbirth and infant death stratified by gestational age’, 120(1).

Selo-Ojeme, D., Rogers, C., Mohanty, A., Zaidi, N., Villar, R. and Shangaris, P. (2010) ‘Is induced labour in the nullipara associated with more maternal and perinatal morbidity?’, Archives of gynecology and obstetrics., 284(2), pp. 337–41.

Wood, S., Cooper, S. and Ross, S. (2013) ‘Does induction of labour increase the risk of caesarean section? A systematic review and meta-analysis of trials in women with intact membranes’, BJOG : an international journal of obstetrics and gynaecology., 121(6), pp. 674–85.


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