Induction of Labour

Why induction is offered

The NHS lists three broad reasons: you are overdue, your waters have broken but labour has not started, or you or your baby have a health problem. Named examples include high blood pressure, diabetes, intrahepatic cholestasis of pregnancy, and a baby who is not growing.

ACOG's list is longer but not different in kind, adding placental problems, decreased amniotic fluid, infection of the uterus, and pre-eclampsia. It also names conditions where induction is not appropriate at all and a caesarean may be needed instead — placenta praevia, a baby lying sideways or breech, a prolapsed cord, active genital herpes, and some types of previous uterine surgery.

The 41-week threshold, and where it comes from

The NHS: "induction will be offered if you do not go into labour naturally by 41 weeks, as there will be a higher risk of stillbirth or problems for the baby."

NICE supplies the underlying data, and it is more reassuring than the headline suggests. Of labours that start spontaneously, 50.3% have started by 39 weeks and 6 days, 82.8% by 40 weeks and 6 days, and 99.0% by 41 weeks and 6 days — leaving 0.9% starting at 42 weeks or later. NICE's instruction to clinicians is to "give women with uncomplicated pregnancies every opportunity to go into spontaneous labour."

What changes after 41 weeks, in NICE's words, is that some risks "may increase over time", and it names three: increased likelihood of caesarean birth, increased likelihood of the baby needing neonatal intensive care, and increased likelihood of stillbirth and neonatal death. Induction from 41 weeks "may reduce these risks", set against its effect on your birth experience.

What induction changes about your birth

NICE requires that this is spelled out before you decide, and the list is worth reading in full because it is the part most often glossed over. Induction means:

• Vaginal examinations before and during induction, to choose the method and monitor progress.
• A narrower choice of place of birth, because interventions such as an oxytocin infusion, continuous fetal heart rate monitoring and epidurals "are not available for home birth or in midwife-led birth units".
• Possible limitations on the use of a birthing pool.
• A greater chance of assisted vaginal birth using forceps or ventouse, "with the associated increased risk of obstetric anal sphincter injury".
• A risk of hyperstimulation with pharmacological methods — the uterus contracting too often or for too long, which can affect the baby's heart rate.
• A labour that "may be more painful than a spontaneous labour".
• A potentially longer hospital stay.

The NHS says the same in fewer words: "induced labour is usually more painful than labour that starts on its own", and "if you are induced you'll be more likely to have an assisted delivery."

One thing induction does not restrict: pain relief. The NHS is explicit — "your pain relief options during labour are not restricted by being induced. You should have access to all the pain relief options usually available, such as an epidural or water birth."

The methods, in the order they are used

1. Membrane sweep

Offered first, and the only step that happens as an outpatient. The HSE: "usually done during an outpatient appointment. This means you will go home afterwards."

2. Assessing the cervix

NICE: "explain to women that a vaginal examination to assess the readiness of the cervix (recorded as the Bishop score) will help to decide which method of induction they will be offered first, and obtain consent to carry this out." NICE describes a Bishop score of 8 or more as generally indicating a cervix ready to dilate, and uses a threshold of 6 to steer the choice between pharmacological and mechanical methods. ACOG uses the same tool, noting "a Bishop score of less than 6 means that your cervix may not be ready for labor."

3. Hormones

The NHS: hormones "can be put inside your vagina using a vaginal tablet (pessary) or a gel, or given as tablets that you swallow", and "you'll usually be offered hormones first to see if they work, unless there's a medical reason you cannot take hormones." The HSE describes the pessary as looking like a small tampon, left in place for 24 hours and removable by a short string, and notes that prostaglandin gel "can take up to 72 hours to work" and may need repeating.

4. Mechanical methods

The NHS names "a balloon catheter (a small balloon, full of water) or an osmotic dilator (a type of sponge)" used to widen the cervix. The HSE explains the appeal: the balloon method "avoids any risk of too many contractions", and may be recommended if you have had one previous caesarean birth or if other methods have not opened the cervix enough. ACOG describes the same two devices, adding that some prostaglandins are avoided after a previous caesarean because of uterine rupture risk.

5. Breaking the waters, then oxytocin

The NHS: "sometimes a hormone drip is needed to speed up the labour. You may also need to have your waters broken artificially." The HSE notes oxytocin "is usually only used after the membranes have ruptured", is given through a drip on the delivery suite, and "is started at a very slow rate and increased slowly until you are having regular contractions." ACOG says contractions usually start about 30 minutes after oxytocin is given.

How long it takes

The NHS is candid: "it usually takes many hours for these treatments to start working. You will usually stay in the hospital maternity unit, though you may be able to go home in some cases." Induction is always carried out in a hospital maternity unit, with midwives providing care and doctors available.

If induction does not work

NICE defines unsuccessful induction as "labour not starting after one cycle of treatment". The NHS: "your obstetrician and midwife will assess your condition and your baby's wellbeing. You may be offered another method of induction or a caesarean section, or you may be able to wait a few hours and then be assessed again."

Where UK and US practice genuinely diverge

On overdue pregnancy the two systems broadly agree — ACOG lists a pregnancy lasting more than 41 to 42 weeks as a reason for induction, close to NICE's 41-week offer.

They part company on elective induction. ACOG describes induction chosen by a healthy woman with a healthy fetus, for reasons such as physical discomfort, a history of quick labour, or living far from the hospital, and states that "labor induction may also be considered for healthy women at 39 weeks of pregnancy to reduce the chance of cesarean birth", while insisting that "elective induction should not be done before 39 weeks of pregnancy." NICE's guideline contains no equivalent routine offer at 39 weeks for uncomplicated pregnancies; its framing is to give women every opportunity to go into spontaneous labour, with the offer arriving from 41 weeks. If you have read American advice about a 39-week induction and are being cared for in the UK or Ireland, that is the source of the difference.

Your decision, at every step

The NHS: "it's your choice whether to have your labour induced or not." And if you decline past 42 weeks, "you should be offered increased monitoring to check your baby's wellbeing."

NICE goes further, and this is the sentence to hold on to: "recognise that women can decide to proceed with, delay, decline or stop an induction. Respect the woman's decision, even if healthcare professionals disagree with it, and do not allow personal views to influence the care they are given." You are also entitled to time — NICE asks clinicians to give you space to discuss it with others and to think, before you answer.